It's pretty simple.
For a high skill ceiling, either everyone has to have lethal weapons and you can kill everyone very fast, or everyone needs to have high mobility/other defensive shit that lets them survive 1v2 encounters against people that can aim. DayZ, Insurgency, CS, CoD, are all examples of the former. Tribes, Quake, Painkiller, TF2 to an extent, are examples of the latter. Overwatch makes sure to limit each class so that they're A) either fucked in a 1v2+ encounter against skilled players or B) don't have enough damage to realistically deal with certain classes.
Then there are some lame ultimates that can kill you pretty much out of nowhere, in the spirit of TF2 criticals. When TF2 was in its prime, I played with the best EU team. When Tribes: Ascend was in its prime, I played with the second best EU team. Played in a dozen of the best CoD1 RO teams, etc. And in Insurgency I'm banned for aimbotting and wallhacking from the only servers that are still populated. Which is to say, I'm really good in different FPS games, and I can see where the skill ceiling potential is without playing it for 200 hours. Overwatch has enough of a skill component in it to have an esports scene, but we'll see. It's like Dota 2 and TF2 met halfway, in more than one way.