I agree. I think the devs are TRYING to match tanks and dps so they have even skill, the question is how are they doing it? The answer is by MMR which is a number that is calculated by evaluating the players individual skill (kills, dmg per second, deaths etc)) and those algorithms are terrible, TERRIBLE at evaluating skill. This is why there is such a huge discrepancy between players like you described.
The algorithms are broken and have never worked and it never will work because you can’t evaluate a players impact in a game by looking at their stats, there’s a million different variables that go in to making a player effective.