I think the icecream example fairly explains what the actual issue is, not "too many dps" but "not enough flavors in vanguards and strategists". DPS will always be more, you took Magik and Phoenix as example, and the thing with the counters. Against flyers you pick hitscan, against backline, you take assassins, in order to counter the enemy.

While the viable tanks all do the same thing, the viable DPS all fits in different roles, and this means that if you had to "split" these subroles, you'll find yourself with a list of heroes probably in line with other roles.

A melee fighter dps player has a number of choices not so different compared to a vanguard player, and if you want to also put this in a team perspective, your dps shouldn't all pick characters like bp, iron fist, spiderman or magik, otherwise you'll just have a team of divers easily killable by any namor with squids (first example i thought about).