I've been around long enough to have seen how comments on the Web emerged from innocuous guest books and a feature in personal blogging and ended up being un-ironically slapped to any 5-line piece of content. Disqus and their ilk exist because of one reason only: convenience. (a) You don't need to install software and a database to store comments, (b) you don't need to maintain that software or worry that it's an att…
Not if you don't store any personal data ("any information relating to an identified or identifiable natural person" as per the GDPR). If you just provide pseudonym and message fields, you have no issue. This is in the spirit of "data minimisation".
The other alternative is of course to remove the comment box and provide some contact info. Works well but people might not be as keen on sending something.