Partisanship is an odd condition. It makes you say and do things you wouldn't otherwise, and think differently too. Some of it's obvious - the lack of generosity, the desire to attack your enemies and defend your allies even when they're not always worth it, and the habit of forming opinions based on what people around you think. None of these should surprise anyone who thinks about what partisanship means for a minute.
There's subtler effects that can be rather interesting, though. Partisanship tends to compress time in a very unusual way. You can't hang around politics for long without seeing that every election gets called "The most important election of our lives", whether or not it actually is. Every opposing leader is some uniquely bad kind of monster, and every friendly leader is the only hope that the forces of purity and goodness have to slay the dragon. The future gets subsumed into your ideology("We only have a chance if [GOODGUY] wins the election!"), and the past gets mined for a few examples that support your thesis("Remember when [BADGUY] won the election and there was an earthquake the next day?"), but there's no sense of perspective, no sense of scale. Everything is right here, right now, this race, that person, now, now, now.
When you step back and think about things from a distance, it looks very different. For example, I first got seriously involved in politics during the early GW Bush years, around 2002. I remember a lot of people on the left who were 100% sure that he'd never leave office peacefully and would be a dictator forever, that he was simultaneously a simian with an IQ below room temperature and an evil mastermind who could trick a whole nation into wars without breaking a sweat. Millions of people took to the streets to accuse him of this and more - I think he got called everything but late for dinner at one point or another, and if you put all the Hitler mustaches that got drawn on pictures of him end to end, they'd probably reach from here to the moon.
Of course, it didn't get posted on Facebook, so it didn't happen. Right? Because I see a lot of people today who sure want to forget it. If Upworthy had existed in 2003, they'd have been near the front of the Chimpy McBushitler crowd, but today they're posting stories like this. A throwaway mention or two that they didn't like him much, and then a bunch of his comments that are civil, wise, decent, and humane.
At first glance, this looks like a long-needed return to balance. Maybe we can finally stop condemning people as inhuman scum and take a reasonable, balanced perspective on their merits and their flaws. Once you take someone out of the immediacy of partisan politics, get them away from the rough and tumble of fighting over news cycles, and have a chance to realize that your opponents deserve a bit of generosity, we can get past all this mud-flinging and reach a sensible consensus. Right?
Yeah, I'm a dreamer. I know. This has nothing to do with moderation or balance, though that is a long-term side effect. I think the real reason for the article is one line near the end:
"It's almost unthinkable that these statements would come from President Bush's successors in 2016."
This is why the article exists. It has nothing to do with Bush - it's about Trump. It's about taking the negative feelings that they built up towards Bush, and saying "You know how bad the old guy was? The new one is even worse!". It's about trying to take those old feelings of hatred towards the other side that are obsolete and useless to a partisan, and turn them into new feelings of hatred that can be mined for partisan advantage.
Perhaps I'm being unkind to Upworthy here(though if anyone deserves unkindness, the inventors of the clickbait headline do). But this is something I've seen over and over. Every partisan I've ever seen who elicits strong feelings in their opponents is rehabilitated almost instantly by people on the other side as soon as their successor needs a good smearing. Every time their successor is "just more of the same" if the successor is boring and has no traits worth attacking, or "somehow even worse" if they actually have opinions of any sort.
To be clear, this is in no way limited to the left. Ontarians can look, for example, at how Wynne has been treated by the PCs - she was McGuinty Jr. for the first year or so, until bad things started happening that could be pinned on her(even if the biggest, absurd hydro rates, was mostly McGuinty's doing), at which point she became "even more corrupt", "even more out of touch", et tedious cetera. I've seen multiple right-wing strategists describe this process of building up enemies as a fundraising and voter mobilization tactic pretty openly. I'm sure if I got involved in a left wing party, their guys would say the same. It's a strategy - its goal is to be successful, not to be nice, or even accurate. It's about winning. This is another example of why successful political leaders should usually be lacking in principle, so they can do things like this and still be able to function.
Even if this is a functional strategy that all sides use, though, we are under no obligation to take it seriously. Those who know me know I've got fairly strong partisan leanings, but I've always made a point of keeping my identity small and not tying it too closely to the party. I've given at least brief thought to voting third-party in most elections I've ever voted in, I roll my eyes at the hyper-partisans on my own side, and I make a point of discarding the opinions of anyone who doesn't disagree with "their side" on at least one or two issues.
When it comes to rather transparent nonsense like this, just ignore it. Remember that the bad guys that your side builds up as bogeymen do probably mean well. Remember that the last one did too, and that most people are a lot more balanced than their opponents give them credit for. Heck, even Hitler ate sugar. This doesn't mean you need to stop fighting them, but remember that you're fighting someone who means well and is really bad at it, not someone who wants to burn the city down just to provide a good backdrop to their fiddling. Go find out what the good things about them are - give yourself the ability to complement them if you ever need to, and make sure you'll never be surprised by the fact that good things can be said by people with bad opinions. Don't stop standing up for what you believe, just make sure you're being smart about it.