I'm not sure why more processors aren't tightly integrated into memory (and vice versa). Physically separating processor and memory with slow package pins mean

I'm not sure why more processors aren't tightly integrated into memory (and vice versa). Physically separating processor and memory with slow package pins means caches and all the real-time headaches and complexity and die size / cost issues they bring with them. When I assemble a new PC I almost never increase the memory down the road, so it might as well be on the processor die.