At this point, I would much rather use any x86 based laptop instead. Their price-to-performance ratio's have significantly increased since the first RPI was introduced and for a 100$, you get a much better package. So, unless the ARM ecosystem grows to allow for pluggable, extensible and better performing solutions than the latest entry-level celeron or ryzen based systems, I am no longer investing into it.
Once any of those requirements is loosened the other options start to look way better. So if you want a low power ARM computer and aren't concerned with the size as much, you can always get an old used Chromebook instead - which is well worth the money, but only IF you need any of the extra stuff it comes with (monitor/keyboard/mouse/battery/storage/camera/etc etc...). If you just want raw compute, then you can just buy an old x86 box like you say, but that will cost you in power and size.
I think some people just like to tinker on these little gizmos specifically, though. You read blog posts about running Kubernetes on Pis, and the immediate question is "why would you do that rather than just virtualizing stuff on an old x86 box?" The answer is really just "well, it's fun to work with little computers" which is presumably a factor for a lot of people.
[0] https://store.pine64.org/?product=rockpro64-4gb-single-board...