As a point of comparison, Microsoft ships its OS across a variety of manufacturers and largely keeps it maintained across them (give or take some exceptions like enterprise environments & the like).
Even unlocked Android phones purchased independently of carriers have inconsistent lengths of support, so it doesn’t seem to be entirely a result of carriers, so…What happened here?
But your answer could be interpreted as “a FOSS OS can never maintained for a big variety of hardware over a long life cycle” which would be totally wrong. Android’s driver situation might be shit but that has nothing to do with an “open system” vs a “closed system”. My knowledge regarding this topic is not deep enough to give a perfect answer but I think other posts here sound more plausible.
I don’t wanna sound too defensive but I did say this
I agree that I can reword it to make that clear, but I don’t think, nor do I hope anyone will make that conclusion about FOSS…