Its not just rv folks that found out by actual experience pure silicone didn't bond well when used as a sealant. That depends on the class silicone used.
GE has three different class of silicone sealants for exterior use.(doors and windows)
a all purpose class 25...
a advanced all purpose class 35 with 5X stronger adhesion...
a supreme silicone class 50 with 7X stronger adhesion...
Probably why some silicone users had no adhesion issues and others did. I'm sure other silicone brands are about the same as GE.
Lots of info on the net from rv forums/boating repair shops/construction trades/etc about wrong class of silicone lack of adhesion issues.
