I agree with you, but for me it’s a risk and liability thing. It’s also a function of what I have had the experience doing...I can actually hang/tape/mud drywall semi decently, DEFINITELY not as fast or as good as a pro. Same with tiling, flooring etc , most cosmetic things. But I’ve never had the opportunity to learn much about plumbing or electrical. And those could have huge consequences if not done properly.