You are talking about a problem that is independent from the dps output of the classes: players aren't told how core mechanics work. This has been addressed in the recent updates with the adventure guide and the beginning of EoD. You have to seperate this from the damage balance though, because a dead dps doesn't do any damage, regardless of potential.
On the dps side of things there are also two main aspects: baseline and maximum potential (floor and ceiling). You are talking about low performing players, that are on the floor side of things. But neglected the ceiling part. If you raise the ceiling (like soto did) you trivialize a huge part of the content for most players. Especially in raids there are mostly mixed groups of players, with low performing and high performing players. If you have just two players doing 80% of the benchmark dps, the group skips entire parts of the fight ruining the encounter as it was intended. This also affects the low performing players, that are in the group as well.
Now let's talk about the baseline (floor) of dps. Yes there is a big difference between baseline dps and the ceiling you can achieve, maybe they could tweak this a bit for some classes. But in my experience bad baseline dps often comes from bad preparation or bad support. Before last patch I tried to benchmark the power soulbeast standard build on the golem, with only doing sword auto atracks. I did get 17k dps out of it. That's more than enough to beat almost all content. You literally don't have to press any buttons, just do the mechanics.
Heal and boon dps is another thing. It's a shift of focus, your dps isn't that important anymore, now it is keeping the team alive and providing utility. This is traditionally harder than pure dps, because you need to adapt to the encounter you are facing and know the kit you are using. But there are easy variants too, that can provide the core boons without breaking a sweat.
All in all it's not "git gud", but just "git okay". Invest 15min for preparation once to setup your class and you are good to beat any non cm in the game. If you want to get into raids, strikes and fractals invest another 10mins to watch a mechanics video or go into a training raid before joining experienced groups.