Below comes from a Polygon interview:
Jon Spector:
Jon Spector, commercial leader and vice president for Overwatch, said that Blizzard has “put a ton of time and energy into discussing how to make this system fairer for players, how to make sure that we’re preserving the competitive integrity of our game.”
“That observation that Aaron made — about how hero swapping works in reality — was pretty eye-opening for me when we first started working on this,” Spector said. “What we actually see in the data is that a majority of players in Overwatch have a majority of their play time on two or fewer heroes. And you can get to 99.9% of play time for a majority of our players with 12 or fewer heroes. They have a cast of 30 right now, and [when] you look at how people are actually playing the game there, they’re using a couple of heroes for most of how they play. Sometimes they’ll swap and they’ll add in a couple more heroes.
“So when we say, ‘Is it actually going to impact the play experience if someone has 34 out of 35 heroes?’ when we look at the data, we feel really confident that it’s not going to.”
Aaron Keller:
Keller said that as Blizzard has designed and rebalanced heroes for Overwatch 2’s 5v5 team composition, it has strived to make the game “a little bit more organic and a little bit more fluid,” and to “decrease the reliance on hard counters.”
“There will still be some of those in the game,” Keller said, “and there will probably be times in the future where we develop a hero that might have a new mechanic on it. It could take us a little while to get our head around the right way to handle that hero. But generally […] we still think that team compositions, hero picking, and counter-picking is an important elements of the game; we just don’t want it to be the only correct answer.”
“Even with this change of putting heroes in the battle pass, we think that with all of the other systems that we have in place, and with the additional ways of unlocking heroes and some of the ways that Overwatch has changed over time and the way that we’re changing Overwatch for Overwatch 2 […] we will still have a highly competitive game, even though some of the systems and some of the decisions that we’ve made to get there are different than what we started with.”
I like how Jon basically gives up on his explanation and pretty much says “uhh it’s just one hero dude”.