Ehh, it depends.
I did enjoy, back in the day, upgrading my Mac's RAM at the halfway point. I'd buy a new laptop every four years, and two years in, I'd increase the RAM.
But yes: it would only improve one part of the equation.
This is true to a point. But if an app reads 8 Gigs of data, it'll run faster on a machine that physically has more than 8 than on a machine that doesn't, because the OS will have to swap less / be able to cache more. Higher speed of the RAM, CPU, SSD can only mitigate that. Higher RAM will massively improve performance in such a scenario.
We can argue back and forth how likely that scenario is, and we have been for 67 pages, but that doesn't mean it isn't there, and increasingly, it's relevant for consumers as well. If you keep a Mac for the average three to five years, 2023 (through 2026-28!) is just about the latest I'd consider 8 to be acceptable for the low end.