I'd say that regardless of the brand, X86 CPU don't need to be upgraded as often as they used to. No awesome new extension like SSE or something like that, not much more powerful, power consumption not going down significantly. If you don't care about power consumption, the server CPU will be more interesting, there's no doubt about that.

My issue with surplus server kit at home is that it tends to idle at very high power usage compared to desktop kit. For home use that won't be pushing high CPU utilization, the savings in cost off eBay aren't worth much.

This is also why you're seeing AM5 on server motherboards. If you don't need to have tons of PCIe lanes--and especially with PCIe 5, you probably don't--the higher core count AM5 chips do really well for servers.

They're still useful, but they're not competitive in overall performance with recent CPUs in the same category. They do still compete with some of the budget and power-efficient CPUs, but they use more power and get hotter.

That said, those 4th gen Intel CPUs are indeed good enough for most everyday computing tasks. They won't run Windows 11 because MS locks them out, but they will feel adequately fast unless you're doing pretty demanding stuff.

I still have an i5-2400, an i7-4770K and an i7-6700 for occasional or server use, and my i7-8550U laptop runs great with Linux (though it overheated with Windows).

I buy AMD now though.