I do not know what benchmarks do you have in mind.
All the benchmarks that I have ever seen published about AVX-512 vs. AVX2 on AMD Zen 4 have shown better performance on AVX-512. Very frequently, the AVX-512 performance was not a little better, but much better, despite the fact that on Zen 4 both program versions use exactly the same execution resources (but AVX-512 programs have less instructions, which avoids front-end bottlenecks).
for the simplest cases it will be about the same speed as avx2, but if you're trying to do anything fancy, the extra registers and instructions are a godsend.
I do not know what benchmarks do you have in mind.
All the benchmarks that I have ever seen published about AVX-512 vs. AVX2 on AMD Zen 4 have shown better performance on AVX-512. Very frequently, the AVX-512 performance was not a little better, but much better, despite the fact that on Zen 4 both program versions use exactly the same execution resources (but AVX-512 programs have less instructions, which avoids front-end bottlenecks).
for the simplest cases it will be about the same speed as avx2, but if you're trying to do anything fancy, the extra registers and instructions are a godsend.
Well, try it out for a realistic program.
It makes for nice looking code, yes. But is often slower (for various reasons that are well understood by now).
Please mention some of those reasons.