Intel's current generation CPUs have the same dual-channel LPDDR4X memory that Apple uses. Memory is not "on the same die" for either company because you don't make DRAM on the same process where you make CPUs.
The grandparent used the wrong term. The memory isn't on the die, but it is in the package (MCM). I don't think that provides faster throughput, but it should help latency.
Regardless, the big win was giving unified access to that memory using a memory fabric. That lets the GPU (for instance) access graphics assets with no copying - it just uses them in place.
AMD can absolutely do the same thing, if it desires. Intel can too, but it has a hill to climb WRT GPU performance.
Apple's AI chiplet is another matter...
The point they can’t process as many instructions per clock cycle and there’s nothing they can do about it. They can’t match the M1’s performance per watt.
And certainly there’s no Intel/AMD laptop processor with 8 or 16 Gb of RAM via a 128-bit memory bus on the same die. Same thing with a 16-core Neural Engine with an OS with the APIs to take advantage of them.