Well, I look at it like this
For Diamond and below, Double Shield was actually one of the most diverse periods in terms of hero picks. If you go back and look at that period, pretty much every tank was viable in these ranks except DVa and Winston (and Winston has never been very viable in mid and low ranks, so nothing new), and every support was viable except Zen and Brigitte (Brigitte as a result of an at-the-time UP rework, and Zen is in the same situation as Winston). DPS diversity was more-or-less the same as it’s always been. It was probably the most balanced period in these ranks since pre-Dive, and that was with fewer heroes.
The issue was that high ranks had another oppressive meta, like they have since Triple Tank w/ Ana and likely would’ve always had were it not for hero bans. It seems to be a great shame that the enjoyment of 95%+ of the playerbase was butchered on account of this playgroup, which largely stemmed from the combination of Sigma + Orisa. So… my thought is, why not just use hero bans (restricted to high ranks as they are now) to address the meta issue without massacring the experience for the vast majority of the playerbase? Especially with queue times being an issue, taking steps to maximize tank/support retention by not making bad changes to their options and pigeon-holing them into a handful of heroes seems like a smart move, but it’s not what we got.
I’m not saying every change over the past 10 months has been bad, but a lot of the “good” changes were ones that could’ve and should’ve happened without all the bad changes… and unfortunately, for me at least but many others, too, the bad changes greatly out-weight the good.
Also splitting OWL balance is, to me, common-sense. Even if you’re a diehard top-down balance advocate, balancing around an environment in which players basically train in and play the game as a full time job, which prioritizes entertainment value over actual balance, and in which team coordination is an at absolute maximum doesn’t make sense. It’s not reflective of ladder play at all, which is why you see things in OWL & other pro leagues that rarely appear even in GM, like when Sombra was actually good during GOATS (she was barely scraping the bottom of the barrel in GM) or like GOATS running Zen (ladder GOATS mostly ran Ana, because… well, unless you have the team coordination to capitalize on Zen, the greater healing and anti-nade were just leagues better). That doesn’t even acknowledge that somewhere around 85% of players rarely, if ever, actually play the meta, so balancing around the epitome of the meta and directly impacting the countless people who don’t play it seems a little ludicrous.
I think an alternative solution would be just splitting Competitive balance from the rest of the game, too. Create an “Unranked” (basically RQQP now) as the sweaty-but-not-hardcore sweaty mode and let the QPC fans have Quickplay, and balance those more for the casual crowds while balancing Comp for top-end 
There are a few ways to handle it, but Blizzard is also highly insistent on a “unified” gaming experience (which is… bullhonkey for a few reasons), which limits them needlessly.
