I know some people say never house together but it's really just "beginner's shouldn't try this" talk.

There's been many debates of it so I don't want one to start here. There's a nice one on it in the Advanced Husbandry forum.

Even if you were a seasoned owner and wanted to try multiple housing, you'd still need to quarantine a new snake alone for a period before introducing it

Don't try multi-housing because of financial contraints. If you can't afford to do it right, just don't do it.