It would give a chance to for a counter pick set, which they MAY not be able to switch to stop.
It would open up counter meta’s which couldn’t be just blocked out.
Say for instance, people were running a rush comp, and you COULD switch to dive, since, not all their heroes are in the rush.
But, the moment you do, you would EXPECT a switch to dive counter, but…
If there isn’t a lot of dive, it could have been blocked out by their own team picks.
Which means you can dive, for this map, then the selection starts again, and you have a choice of keeping running dive, (depending on if you think their team will pick up Anti Dive as a set or not).
But it gives you a chance to run off meta comps, which are only off meta BECAUSE they can be counterpicked so easily.
If the hero pick set you have is small enough that you can’t cover all of the counters to different comps, then you are letting those comps be a viable strategy, where they were not before.
That is the genius of this. The moment you HAVE a meta set which people are running, you can counter pick it for a map, and they don’t have a reply right away.
Which opens a lot of options, which would normally be closed.
Meta set picks become dangerous, because a weakness to them, which would normally not be viable, because it would be easy to counterpick is now on the table as playable.
The danger is “win in the spawn room” situations, but, anything which opens up the meta wide open will do this.
For UI, I am guessing that in spawn, you will see in your hero select list, that the ones you team mate has selected is highlighted.
Since, if they are s76 in case you need hitscan, then you may want a different backup hitscan yourself, since, you may BOTH need to run it.
It doesn’t mean you CAN’T select it, but, it means you are warned that you could end up in a situation where you can’t run one of your picks.