It is now generally understood that the chemical softeners found in vinyl toys will dissolve silicone not only when in direct contact, but also when residues are present on surfaces or even in a shared water bath. Back when silicone toys were emerging on the market, vinyl was the predominant material for adult toys and took up most of the space in people’s toy chests. My hunch is that most just threw their toys into one box as they always had done with an unpleasant discovery of gooey toys when play time rolled around again. Silicone lube was also emergent at this time and becoming more commonly used.
I pair this destructive reaction to vinyl plasticizers with the known scientific principal that a cured silicone will have the propensity to absorb silicone fluid to come to what I believe is the source of the reason the lube was pointed to as the culprit. Being absorbed into the surface and released later, would almost ensure a residue would always be left on the toy so that when this contact burn with vinyl was discovered, the toy would also be covered in a light film of oil, and the false association made. Again, all a hunch, but in light of the fact I’ve never had any damage to my toys attributed to silicone lube, ever, and the current use of silicone lubes with no adverse affects on the few other brands I know that use 100% Platinum cured silicone, it’s my best assessment of the origins of this commonly held belief.