The thing is that people have been running small inns/B&B's (and renting vacation homes) forever as something between a formal business and some money on the side. There were online listing services before AirBnB and paper listings in various tourist catalogs before that.
AirBnB is just another listing service in that context. Today, if you run any sort of bed and breakfast and can't deal with computer listings, online reservations, etc. you're at an enormous disadvantage compared to your competition. I know that if I can't immediately check availability online and have to email--or heaven forbid call--I'm much less likely to book your property.
What's mostly different about AirBnB is a lot of the quasi-legal rental of properties that aren't really B&Bs or vacation properties.
It's not just yet another listing. Nor it is about quasi-legal rental.
For the user, it allows to find room by location, enter in contact, book and prepay in a convenient way that is unprecedented.
For the hosting, it allows to easily rent, accept the money and reply to people.
There were simply no service that allowed to neither buy nor sell that easily before.
It had the side effect of attracting a lot of "black market" operations onto it but that doesn't make it about black market (even though it did play a role in the growth). AirBnB is about providing a great service to both buyer and seller.
(Anyway, there's always been a HUGE black market for property rental. The incentive to declare are not worth it. AirBnB barely make the issue more visible.)
AirBnB is just another listing service in that context. Today, if you run any sort of bed and breakfast and can't deal with computer listings, online reservations, etc. you're at an enormous disadvantage compared to your competition. I know that if I can't immediately check availability online and have to email--or heaven forbid call--I'm much less likely to book your property.
What's mostly different about AirBnB is a lot of the quasi-legal rental of properties that aren't really B&Bs or vacation properties.