"Use vim in SSH" is not a great answer to asking for a convenient way to edit a single file, because it requires understanding multiple somewhat-complex pieces of technology that OP might not be familiar with and have a reasonably steep learning curve.

But I'd still like to explain why it pops up so much. And the short version is very simple: versatility.

Once you've learned how to SSH into your server you can do a lot more than just edit a file. You can download files with curl directly to your server, you can move around files, copy them, install new software, set up an entire new docker container, update the system, reboot the system and many more things.

So while there's definitely easier-to-use solutions to the one singular task of editing a specific file on the server, the "learn to SSH and use a shell" approach opens up a lot more options in the future.

So if in 5 weeks you need to reboot the machine, but your web-based-file-editing tool doesn't support that option, you'll have to search for a new solution. But if you had learned how to use the shell then a simple "how do I reboot linux from the shell" search will be all that you need.

Also: while many people like using vim, for a beginner in text based remote management I'd recommend something simpler like nano.