That's actually a good thing. That's how you get a ton of DRAM without it costing a fortune. M2 Ultra is able to get GPU-like 800GB/sec with DDR4. From that it follows that if you can design a specialized chip, you can get a respectable 1 TB/sec quite easily with LPDDR5, provided that you're willing to design a chip to support a ton of memory channels (and potentially also a wider memory bus). In fact, I'm baffled that such devices don't already exist outside Apple's product line. Seems like a rather obvious thing to do, and Apple has a "proof of concept" already. I can think of at least four companies off the top of my head that could do it quite easily, besides Apple.