The most frustrating thing here is that the decline isn't due to a lack of technical solutions. Both AMD and Intel have demonstrated their ability to design highly efficient and compact cores and integrated them heterogenous CPU designs. Both will well be aware of the economics of silicon manufacturing - that smaller dies made using space-efficient cores produce higher yields and lower costs - and that NPUs and ever-bigger integrated graphics for their "headline" offerings is pushing up die size, all while the costs of manufacturing each silicon wafer are also going up. Yet both, to date, have yet to really follow through with a cheap, no-frills design, one that's highly capable for content consumption and basic productivity but doesn't bother with lofty ambitions of content creation or on-the-go gaming.
There is not enough competitive pressure for Intel/AMD (or even Qualcomm or Apple for that matter) to design a relatively performant, "no frills" CPU for a highly cost competitive price. That's why there is a giant gulf between Alder Lake-N (formerly Celeron or Pentium) and their mainline processors.
And laptop OEMs really don't want to deal with low ASP SKUs anymore than they have to. They would much rather upsell "new tech".