RSA is old (literally from 1977!), slow (because huge keys are required to make it non-trivial to brute force), and overall less secure than modern elliptic curve cryptography.

As I said though, I missed that they also have EdDSA and ECDSA keys when I skimmed the article during my lunch break. Since the RSA key is only for backwards compatibility it isn't an issue. Thank you for pointing that out to me.