Twitch for example will allow you take over usernames of accounts that are unused. Also having a good name is less important than you think. Most people don't navigate by going to exact identifiers. They just type the name of the thing into a search and relevant results will be returned. Dead or useless results should not rank high.
So I should decide to be beholden to the whims of search engines and not have any other way to direct people to my content (besides QR codes maybe?)
I'll admit it works sometimes. "news.ycombinator.com" is not as memorable as "hackernews.com" would be. But I like being able to have my website be chadnauseam.com (the name was unavailable on reddit), I like that no one is going to decide I'm not using it enough and take it away from me, and $1/month is so trivial that I think it's worth the benefits.
Besides, if you don't care about having a short and memorable name people can type exactly, why not just host your site on the free subdomain vercel or heroku gives you?
