Utility of rarefy function and rarefaction?

Hi @sabahzero,
Great question! I think it is too early to call rarefaction obsolete, though it is certainly on its way out the door. Your question is a replicate of some previous posts — see this response:

So it is still quite useful to expose functionality that a very large number of users still rely on.

Similarly, QIIME 2 has several methods for OTU clustering, which is still very popular (and useful for some applications), even though denoising methods are theoretically much better.