Those machines multiplexed the bus to split access to memory, because RAM speeds were competitive with or faster than the CPU bus speed. The CPU and VDP "shared" the memory, but only because CPUs were slow enough to make that possible.
We have had the opposite problem for 35+ years at this point. The newer architecture machines like the Apple machines, the GB10, the AI 395+ do share memory between GPU and CPU but in a different way, I believe.
I'd argue with memory becoming suddenly much more expensive we'll probably see the opposite trend. I'm going to get me one of these GB10 or Strix Halo machines ASAP because I think with RAM prices skyrocketing we won't be seeing more of this kind of thing in the consumer market for a long time. Or at least, prices will not be dropping any time soon.
You are right, hence my "in a certain sense", because I was too lazy to point out the differences between a motherboard having everything there without pluggable graphics unit[0], and having everything now inside of a single chip.
[0] - Not fully correct, as there are/were extensions cards that override the bus, thus replacing one of the said chips, on Amiga case.