"Exclusively" is the key word. Whether youtube-dl is designed to "exclusively" be used for legally permitted uses is a matter for a court to decide. The RIAA's claim listed several reasons why it believes this is not the case.

The DMCA as written is a little more nuanced, but on whole the laws serve the same purpose.

>Exclusively

Not the tool is meant here but the User, and you know it.

It's legal to record radio, and record/download Youtube videos, if you don't redistribute it (outside Family and Friends

The distribution of youtube-dl itself is what's at issue, not the use of youtube-dl or the distribution of files downloaded with youtube-dl.

Just read that article:

https://joindiaspora.com/posts/808cf690f8e801381778002590d8e...

And why is that not a issue anymore? (hint it was):

https://en.wikipedia.org/wiki/Libdvdcss

The RIAA is specifically making the allegation that "the source code was designed and is marketed for the purpose of circumventing YouTube’s technological measures to enable unauthorized access to our member’s copyrighted works" [1], justified by the references to copyrighted works in the youtube-dl readme and source code. If it wasn't for that, it'd be much easier to argue that it's designed for non-infringing purposes only (or one of the other exceptions to the DMCA's TPM clauses), like you could plausibly argue for libdvdcss.

[1] https://github.com/github/dmca/blob/master/2020/10/2020-10-2...