More people would try playing an instrument if they could borrow one to try it out. I already play several, but I’m running out of money and space for more. It’d also be nice to pop down to the library and check out the one I’m currently obsessing over to see if I want one permanently. Hell, I’d donate ones I hardly ever use to add to the diversity. This wouldn’t replace buying instruments any more than regular libraries ended book stores.
With most woodwinds, you probably have to get your own reed for ~3,50€. But the rest can be cleaned well enough.
When my concert band lends out instruments they have to get a professional service at the local music store when you return them. They’ll replace any consumable parts that are missing, if you haven’t already.
Of course that would probably be a bit more difficult in a library setting, where the lease lasts only a very short time.