That the “Tank Pathway” you describe is an alien concept in games that are primarily FPS games.
I miss any "Tanks from FPS games"?
And pretty much exclusive to RPG/MOBA games.
And that yes, Overwatch was originally envisioned as an MMORPG, largely made by former World of Warcraft staff.
But also with the advent of Role Queue, this game is going to live or die based on it’s queue times. And easily over 60% of it’s players prefer shooting stuff.
So pretty much the only way they solve queue times is by making DPS players play with playing Tank instead.
Which is fine, considering 222 prevents stacking 3-4 Tanks on a team. And “beefy character with considerable firepower” is a tried and true concept that works with virtually ever other “Primarily FPS game”.