Saying that a false statement of an opinion doesn't save it from being false, either.
(Not that I'm saying you, specifically, do that, below...)
You are relating an opinion that sounds like it involves some facts, and you are setting it in the context of 4e being NOT-D&D, but presumably you don't find any similar issue in 5e (or 3.5?). And, that may need some clarification.
Now, within a given source, there are some /very/ similar powers, where you could do exactly that. File off the class & power name, and you have two martial encounter weapon attack powers that, say, let you shift half your speed and attack an enemy for 2W damage. Only the fluff text is that different. OK, maybe one uses STR and the other DEX (in 5e, that's just called a finesse weapon, not much of an issue). There aren't a tremendous number of such powers though, and there really aren't many that cross source lines.
So, like I said above, even I feel the aesthetic impulse to just consolidate powers by Source. I mean, that's my opinion on the matter.
OTOH, you have the Sorcerer, in 3.5 and 5e, alike, he had no spells that were unique to his list ("he" being Hennet, of course), likewise, in 5e, the Sorcerer has no spells that are only sorcerer spells. Not a problem, both eds are Really D&D, neither was Warred against (much, 3.5 caught some flack as a 'money-grab,' and grognards groused about it's 'grid dependence'). Yet, that some sorcerer spells, stripped of identifying marks and fluff text might be close enough to "look much the same," mechanically to Warlock or Wizard spells was an issue in 4e?
Or have the many spell-list duplications in past editions, in general, and the Sorcerer, in particular, always been appalling to you, as well?
Or is this opinion getting into the point Cambell, made, above, about 4e seeming more concerned with differentiating classes from eachother within roles, and other eds seeming more concerned with differentiating between casters & non-casters?