New for performance machines maybe. I remember "integrated graphics" when that meant some shitty co-processor and 16 or 32MB of semi-reserved system RAM.

Nope, it was common in 8 and 16 bit home computers, and in respect to PCs themselves graphics memory was mapped into the main memory until the arrival of 3D dedicated cards.

And even with 3D, integrated GPUs have existed for years.

Like pretty much every game console.

The CPUs with iGPUs didn't also have the memory on-chip. The Nintendo 64 did. Not sure about the old home computers, but I thought those had separate memory usually.

Of course not, because they are not designed as SOCs, the only memory on chip is cache, it doesn't change the fact the memory is one whole block shared between CPU and iGPU.

Apple does not have the memory on-chip (on the same die as the CPU) either.

It's not new for PC to block user ram upgrade