Oh, now this I agree with.
I just disagree with your timeline. It's been this way since 5e was released. 5e was always super high magic right out of the gate. To the point where it took multiple supplements to even make a dent in the imbalance. And it wasn't much of a dent at all. We're still at the 80% magical classes level we were at 5e's release.
For me, it's hilarious. One of the biggest gripes I saw about 4e was how they turned every class into a caster, when that was totally untrue. Now, 80% of the classes are magical and most of those are outright spell casters, and everyone thinks that's great!!!
AFAIC, the ship sailed years ago on trying to make 5e less caster heavy.