It’s not difficult, but I can list at least two reasons why not
Many people set up a website for a school project and after receiving a grade simply leave and leave all the files on the server, etc.
The server has to serve a large number of websites that nobody actually uses.
As admin mentioned the number of certificates is limited
and having a TLS auto-install for a bunch of abandoned sites makes no sense,
that’s why the manual process is a simple solution because whoever needs it and has a live website will come and ask for a certificate
Another reason is that there should be a difference between a free service and a premium one
The majority of the income for InfinityFree is advertisements, because advertisements are served within the Client area and in other places, and the goal is to get people to visit those places
otherwise, who would pay for this forum, various servers and the rest?
and it’s getting harder anyway because of various ad blockers and def. browser settings.
imagine it like this:
You make some tool on your website and you pay the server
and if nothing else, you try to at least cover the costs of that server by serving ads
Would it make sense for you if your server does everything automatically and people don’t have to come at all?
Very soon you would be in the financial red and would have to close the website