Homes are not more problematic MrMet. It becomes a problem, when you hire someone to install something, and they either do not follow proper procedures, by making sure that they have a water tight seal, when penetrating the skin of the envelope of a structure, especially when they place the dish mounts on roofs. Chimneys are used all of the time for Antenna's, due to most nowdays that have vinyl covering, are built as a part of the house structure.
When the Chimney is made out of brick, then you can run into problems, that you do not know when the last inspection of it was, how sound it may be at the footing, etc. A lot of brick chimneys have been blown over during high winds, due to undermined at the footings, or allowed to pull away from the structure.
As for the whole argument of not wanting to place the mount against the vinyl. Yes, it can push the vinyl siding against the OSB sheathing, but just like when you place anything mounted on the outside of the structure, you just deal with it. Even if standoffs are used, you never cut into the vinyl siding to attach them, you just lag the against the house, towards the top of the vinyl edge, not towards the bottom, due to there is more surface against the sheathing at that point, so you are not causing the vinyl to be pressed against the house. As a homeowner, I personally supervised my dish installation, and showed the installer where to mount it, so that it would have grabbed into the two 2x4's on that edge of the roof line.
I as a homeowner though, hate having to climb over six feet on a ladder to do anything, and have had to go as high as twenty feet on my home to do maintenance, along when we took down the old antenna mounted on the house. The standoffs are still on the house, so if I ever did want to mount another antenna on the outside I could, but personally I am not climbing on my roof to do any work on it, due to it is way too steep.