It's usually a matter of efficiency when it comes to turning items into multipurpose stuff imo. Yeah I guess some can work with the same efficiency as others, but some can be pretty below standard hence why manufacturers still create individual items for them. Heck even some of the "all in one" products being advertised sometimes suck at doing their job just because they want to be used for everything. It can work for some, but it's definitely not going to work for all, hence why it's still relevant to have specific products catered to specific problems.

Personally, I'm not against it but if given the chance, I'd much rather use specialized products just to decrease the hassle of thinking if I fucked up something or not by using a half assed product instead. Emphasis on given the chance.