I am ballmain in masters and only swap very rarely, even if I have a lot of counters. Many teammates always tell me to swap. Personally, I want to learn to play with ball, no matter what the enemies counterpick, because I think individual skill is more important than always being flexible and counterpicking.
I think the best balanced take is to learn 3 heroes well that can fit in most brawl/dive/poke comps. One tricking will probably get you further, as you’ll learn every situation for that character and naturally become very fluent with them. Like others have said though, if you’re equally as good at wrecking ball as your are sigma, but one fits the team comp better or can counter the other team harder, then that hero has a natural edge to them if all else is equal.
Better to master 2 or 3 heroes than try to flex all of the time.
As a Lucio main, I know I can perform WAY better on Lucio against his counters than I ever could on Ana or Bap, for example.
I’ve been playing flex for so long that I can play multiple hero, while I agree you should push yourself and learn how to play against your counters, if they are full countering you then there’s only so little you can do at that point where it just makes sense to switch to get any sort of value