Right but not realky. Fun is subjective, so you have to manage expectations. But that's for you as a DM and your players to work out. What works for Mercer or paid dms may not work for me you.
Absolutely true, but that doesn't mean a given GM has to just come up with everything ex nihilio. Chances are, invidual group or no, the issues you're having are not things that never came up before, and finding how other people handled them can be useful.