You’re probably thinking of Intel and AVX512 (x86-64-v4) in which case, yes it’s pointless because Intel screwed up the implementation, but on the other hand, that’s not the case for AMD. Of course, that assumes your program actually makes use of AVX512. v3 is worth it though.
In any case, the usual places where you’d see improvements is when you’re compiling stuff, compression, encryption and audio/video encoding (ofc, if your codec is accelerated by your hardware, that’s a moot point). Sometimes the improvements are not apparent by normal benchmarks, but would have an overall impact - for instance, if you use filesystem compression, with the optimisations it means you now have lower I/O latency, and so on.
More importantly, if you’re a laptop user, this could mean better battery life since using more efficient instructions, so certain stuff that might’ve taken 4 CPU cycles could be done in 2 etc.
In my own experience on both my Zen 2 and Zen 4 machines, v3/v4 packages made a visible difference. And that’s not really surprising, because if you take a look the instructions you’re missing out on, you’d be like ‘wtf’: