I sort of agree.
What I think is that, ideally, D&D need to PICK A GODDAMN LANE < honks horn repeatedly >
D&D currently, and this is particularly the case in 5E, does a weird thing where randomly some classes, and some archetypes are in-setting things, which have a definite, comprehensible and reliably meaning, and others are merely mechanical frameworks, which might be used for anything which fits within that broad mechanical conceit - they're almost like 4E's roles, more than actual classes.
D&D is thus basically swerving all over the road on this point, or at least repeatedly drifting over the center-line. They could, however, pick a lane.
Lane 1) Classes become largely mechanical frameworks, to be re-flavoured at will, with little/no hard link to the setting. Ideally classes would be re-designed a bit at this point as well. Whilst some people will say "why not go points-based?" I'd say, because everything points-based is a total balance/min-maxing disaster of the worst kind. Keeping classes, at least in the background, means you'd be able to have something which was both more accessible, and more flexible than what we have now. You'd obviously have examples which showed really simple/obvious ways to use the frameworks, but they'd be options, not fixed.
Lane 2) The Earthdawn lane, you make classes very much not mere frameworks, but actual things. This too would probably involve re-jigging the classes a bit, and would probably involve some settings simply not having certain classes and archetypes by default (always available if the group wants of course). It would also mean less compatibility of older settings, but I'd be fine with that. I'd kind of want to do it with every class, too, but there is perhaps another way:
Lane 3) There are some very bland base classes which are clearly just mechanical frameworks and don't need to be tied to the setting because they're just that generic (Expert, Warrior, Mage, and Partial Class), but all the actual magic-magic of setting is extremely specific so tied to that setting, and there are also some very specific setting-tied classes, just for that setting, in addition to the base classes. This is the approach Worlds Without Number* takes.
* WWN is a fascinating combination of OSR and modern concepts, the only place I feel it seems a bit confused on is healing, as it takes a very 2E approach to natural healing but a 5E approach to magical healing, which basically means a group with a healer will be 5E-ish energizer bunnies, leaping off the floor back into the fray (or at least fully recovering between fights), whereas one without will be 2E-ish dullards, ruined for a week or more by a single PC being downed.
