well, as far as starting out with an estate or follower, i think thats what background traits are good for. Which aren't part of true 20, but i quite like them. I have no problem with people sponteanously learning feats or even supernatural powers. I don't even need a retroactive reasoning, i have no problem with a character suddenly doing something because they felt they might be able to, or whatever.
However, if my players had been trappesing about in a duengeon and one got a manor, it would be a bit weird. I mostly don't like them as feats because it is not controlled enough, while i realized as a GM i can veto feats, i don't like to unless i specified it before hand. I recognized their use, i was just curious, i am not really looking for an argument for or against, just other peoples thoughts and/or alternatives...although i guess that means i am looking for arguments against, i really just like alternatives whether i use them or not