Sure, you could. But this isn't my job, it isn't my career. I just want Nextcloud running on a machine at home. I know linux and docker well enough to validate the ideas coming out of Gemini, and it helps me find stuff much faster than if I had to read man pages or read books.
And I find the stuff that the average self hoster needs is so surface level that LLMs flawlessly provide solutions.
My push back isn't really on the possibility, it's on the irony. Self hosting is for many an ideological act that's about reducing dependencies on big tech, removing surveillance, etc. LLMs are essentially the antithesis of this.
If you're self hosting for other reasons then that's fine. I self host media for various reasons, but I also give all my email/calendar/docs/photos over to a big tech company because I'm not motivated by that aspect.