What makes you think that people at Dell or HP don’t sit around and think about those tradeoffs?

They sell to different audiences though, so maybe optimize for different outcomes. I'd imagine DDR5 is much easier to sell to a "pro-sumer" who games on Windows vs. to a programmer who runs linux and can make an educated decision re: price/perf tradeoff.

Well, there are, but the things considered acceptable tradeoffs (like price/performance) are pretty different.