For the longest time, to the best of my knowledge, instructions provided by GitHub and GitLab, probably the two most popular software with easy to access instructions on generating a SSH keys defaulted to displaying the RSA key generation instructions first instead of an Ed25519 key.

The good news is that GitLab uses Ed25519 keys as the recommended default [0]. GitHub still recommends RSA keys by default [1].

[0]: https://docs.gitlab.com/ee/ssh/README.html#generating-a-new-...

[1]: https://help.github.com/en/github/authenticating-to-github/g...