There are privacy and data integrity issues with GitHub for both enterprise and personal use. Gitlab and other self-hosted alternatives are nearly exactly the same. I don't know if "by harder for me as a user" they mean the web-facing frontend, or something else. And even then something like Gitlab offers the exact same feature set as Github does on the web frontend.

On a sidenote this is the same "but x is so much more convenient" mentality that is driving open source projects to lock all their documentation behind something like a Discord chatroom instead of having a proper docs page or wiki.