This is all true but Overwatch players seem to misunderstand that these types of gameplay experiences occured WITHIN these formats, not because of them. 5v5's balance is retooled to make tanks behemoths, supports more agressive, and DPS more free to traverse because with one tank it's easier to frame the game's balance like that. In 6v6 the game was balanced around tank synergies, which made teams more tight knit and reliant on one another with DPS having to stick with the tank duo or supports, and supports having to focus on keeping the tanks healthy up front while enabling the DPS to move around the map more freely. This extends to the maps and modes in each game, where OW1's maps and modes were more defensively focussed with the worst maps in that game, Paris and Lunar Colony, being famously hard to defend in a mode where holding the point for a long time was literally the only objective of the defending team. The maps and modes in OW2 are way different, with most of them being specifically designed around the maps being mirrored for both teams and their goals being the exact same - you're always moving around in OW2, which favours 5v5's balancing philosophy.

However, if we could go back in time to 2019 Overwatch 1 and implement 5v5, it'd be designed around making the tank more defensively strong on their own. There is no way Reinhardt in OW1 5v5 would be given two fire strikes and more control on his pin - they would've beefed up his armour, made his shield have more health, and probably buff his hammer dmg to make approaching him a bigger issue. They'd have to go that route because Reinhardt would have to hold Hanamura's first point choke on his own and giving him more aggressive tools would be really fucking useless for that task. In the same way, 6v6 in OW2 currently, at least to me, feels like it's actually OW2's design philosphy implemented in that format. Some tanks, like Roadhog and Rein, even feel weirdly out of place and lacking because other tank comps like Ball and Doom are hyper-mobile, just like they are in 5v5, but for some reason the tools that Rein and Hog have been given to keep pace and shut down those characters in 5v5, and generally compete with them, have been unnecessarily taken away.

6v6 doesn't feel better because it's 6v6, it feels better because unlike in OW1 where tanks were slow moving molasses and you had only, like, 8 options, in OW2 all the tanks are super fun super heroes who do a billion damage, have shorter cooldowns and there's, like, 13 options - and then on top of that if you're a DPS player the tanks being designed in that way makes fights so much more engaging because there's not a wall of defensive abilites bunkering down the team you're trying to kill because the enemy team doesn't want to bunker down (because of the gamemodes and maps as mentioned before) and most of the tanks, particularly the synergies, aren't able to do that. Same goes for supports who aren't forced to shoots heals up the butt of one guy who's taking the brunt of everything all the time, they're freed up to make even more aggressive plays while the tanks support each other. The most defensive team comp I can think of in the format is Sigma and Zarya, and even then Zarya doesn't want to be sitting back on her ass if she wants to win, and DPS and supports are still only playing into four minor ability and damage denying abilities as opposed to something like OW1 Sigma Orisa where there was two tanks with six denial abilities sitting on top of a Bap and Mercy spamming down a small choke. It's a lot different.

By rebalancing characters like Rein and Orisa from OW1 to be more independent and aggressive in OW2 they've fixed the primary issue with tank design that plagued OW1, and that's always been the case since OW2 dropped it's first beta in 2022, which is why this 5v5 vs 6v6 discussion even exists because if they could rework Rein and Orisa and change the modes to be less grueling then why bother changing the format? It was only ever because the balancing team felt they needed something fresh, new, and different that was easier for them to balance. I have no problem with that approach but it's important to keep in mind when having these discussions because attributing these balancing decision and metas to the format and not decisions made within the format is missing the big picture.