Huh? Really confused how my comment could come across so wrong but I'm not dismissing healers/supports at all. I play PvP healers extensively both in this game (I was a SGE and AST main before 7.1, so I understand the concept - and the fun - of a DPS healer, that's what I loved SGE for and what I am dearly missing after the update) as well as in other pvp games.
My point is not that we need a super neat distinctions where healers don't do anything but heal and tanks don't do anything but tank. That completely misses what my comment is about.
I know that we don't have strict roles but as you say yourself: a class that has it all - damage, heals/mit and utility will have advantages over a class that doesn't.
We still have soft roles though: tank jobs are geared more towards tanking wrt both their kit and the job they most commonly take over in a match. Healers are geared more towards healing which is why they have much more means to keep others (and themselves) alive than red jobs.
And no, there are definitely classes that are not resilient DPS. There's a reason why they are called squishies.
So we also can't say that the distinction between roles doesn't exist at all or is obsolete
This means there still needs to be some balance. A class shouldn't be Reinhardt, Sojourn and Mercy all in one whereas others are only Tracer.
Take (pre 7.1) SGE for example. Technically a healer but had massive DPS. However its DPS was balanced with SGE not healing as much. At the same time it was super squishy so you had to work around that.
And if you look at tanks and healers in Overwatch, some of them are great for DPSing but they often have a much simpler DPS kit. Their strength lies in their ability to stay alive longer and use that strategically to their advantage against jobs that have more extra means of damage but less sustain.
Right now we have some classes that are much closer to being universalists who excel in all three areas. This gives them a clear advantage over classes who aren't.
And that's the problem I was talking about.