How old should my lemm.ee account be to be able to upload photos in posts?

Your personal preference applied to others would sure make all those image-specific communities a bit quiet... 🤔

An image post is one thing, but image replies are over the line.

Context matters here. There a plenty of communities where uploaded pics in posts is the norm and totally fine. Alt text should always be added in some way, but text-only as a general rule is just not practical.