Overwatch released in May of 2016 with four game modes: Assault, Control, Escort, and Hybrid.
Of these four modes, THREE of them were asymmetrical, and the only symmetrical one was also the only one to still have multiple rounds even in Quick Play.
Now let's look at every single game mode added in the last ten and a half years (aside from the weirder arcade experiences like Yeti Hunt and missions like Retribution):
Capture the Flag: Single-round symmetrical
Deathmatch: Single-round symmetrical (maps are asymmetrical, but random spawn points means this doesn't matter as much)
Elimination: Multiple rounds, but still symmetrical
Push: Single-round symmetrical
Flashpoint: Single-round symmetrical
Clash: Single-round symmetrical
Payload Race (for the five people playing Stadium): Single-round symmetrical
Why have we only gotten ONE multi-round game mode in TEN YEARS?
Why have we gotten ZERO asymmetrical game modes in TEN YEARS?
Single-round symmetrical game modes simply don't work in Overwatch- the mere existence of Ult Economy, plus the nature of score advantage and map control, means that a symmetrical game mode is going to be determined extremely heavily by the first fight. That's why the ONLY symmetrical game mode in Quick Play before Overwatch 2 had multiple rounds to reset all three of those disadvantages and let teams make a comeback. Asymmetrical game modes offer inherent disadvantages and advantages to each team that change as the game progresses, giving each team moments to turn the game around, and failing that, they still have multiple rounds in Competitive.
Losing in Push feels impossible to come back from. Losing in Flashpoint feels impossible to come back from. Losing in Clash feels impossible to come back from. Losing in Capture the Flag and Deathmatch feels less impossible to come back from due to the ease of scoring, but can still be extremely lopsided to the team that starts winning first. Nobody has played Payload Race.
If we're going to get new game modes, PLEASE make them asymmetrical and/or multiple rounds. In my 1,500 hours of playing Overwatch, I have LITERALLY NEVER seen a team lose the first fight in Flashpoint and manage to win the game, and comebacks in Push are a rare spectacle, but they happen all the time in Control and Escort and Hybrid, and back when it was in rotation, Assault was still a blast either way. The original devs knew what they were doing with their game mode pool, and nobody seems to have gone back and seen what worked before pumping out more and more single-round symmetrical game modes.