We do a lot to prevent what you're talking about with abandoned GEDCOMs. Many of the problems you see were caused by people who uploaded a long time ago, before things like needing to volunteer, be confirmed, sign the Honor Code, use GEDMatches, etc., etc.
Regarding adopting a profile (becoming the Profile Manager) and getting the whole tree, I'm not sure what you mean. Every profile is managed independently. Maybe ask a separate question in the WikiTree Tech section about this, giving details.