For years, the comment system on this site was essentially webmentions. It worked, mostly because I was able to syndicate my posts to social networks like Google+ (does anybody remember that?), Facebook, or Twitter, and then pull the comments back from there. With time, the social networks became more locked-down and I hardly go there anymore (not only for that reason).
Webmentions are quite a niche thing; not everyone wants to own a website, and even people who do may not have webmention support on their sites. They are still useful to interact with webmention-enabled-site owners, as well as Fediverse inhabitants, but a lot of people around me don’t fall into those categories. I could expand to Telegram, I think. That would require syndicating my posts to a channel there, and pulling back the comments. Looks doable, but to be honest, I don’t feel like putting my effort in another closed platform that is likely to fence up and slowly die, like the others. Meanwhile, there’s another system that should work reasonably well.