Come on, user names don't change. Whether it's Hacker News (as you mention), a reddit username, a skype ID, or your gmail address, nobody expects the "username" to change, it is unique and can't be used if already taken, and everybody uses it as a unique ID on millions of websites without any issue.
In fact, I can't name a single service I've ever used (ever!) that lets me change my username.
Usernames changing is important in a world where peoples' identities change.
People transition and might not want a username based on their deadname. People get married or divorced and change their legal name, which can have ramifications on their usernames. People might just get older, and lose significance of old pseudonyms.
this would remove one of the reasons cited: "People transition and might not want a username based on their deadname." (People go to great lengths to remove references to their "deadname" and consider any mention of it seriously offensive.)
However, despite my downvotes (-4) I am unconvinced by that argument and the other replies. I don't think it's important to do this at all.
You've acknowledged that people transitioning is a huge motivation to change username, and yet say you aren't convinced. Why not? What's the benefit to not allowing usernames to change?
People change usernames because they don't want to be associated with their old username anymore. We shouldn't force anyone to retain that association unless it's overwhelmingly in the public interest to do so. On sites with open user registration I can't think of any possible justification for that. It's only sites with closed userbases where you'd even be able to begin arguing for this, and even there I don't know what argument you could use that would justify it.
> In fact, I can't name a single service I've ever used (ever!) that lets me change my username.
Facebook? Twitter? Instagram? Any of the phone-number-based social apps (which have a poorer UX because of it, but still all allow changing usernames seeing as phone numbers change)? Also I believe Skype does allow changing usernames.
Hotmail Gmail
Seriously why can’t people change their email and keep the mailbox. It’s not uncommon to pick a cute or funny email when you are a teen and want To change when you’ve all grown up
you mention Facebook but isn't it just your display name that you can change? your username (the page listed under "username" if you tap your face in the Messenger app, or on the desktop web app, the page you're at if you click your icon with your name next to the search bar) doesn't change, does it? (maybe I'm wrong and it does.)
Facebook lets you configure both your Name (display name) and Username (the URL slug for your profile) separately. You can even edit your Username right from within Messenger if you want.
In fact, I can't name a single service I've ever used (ever!) that lets me change my username.