I'm a host.
You as individual guests might be worthy of hosting at our accomodation but your friends might be Dicks. Some commentators on here have already illustrated they are too.
Last week I had to break up a fight between what should have been sensible young adults after I heard them bouncing off my furniture, arguing and resultant bleeding on my carpets and being sick all over the place. The "Booking Guest" (i.e. possibly you) was totally out of control and could not control the friends they brought. Thats totally irresponsible.
Do we trust you? Maybe? Do we trust your friends? Who the hell are they? Give us all their contact details, their government Identification, home addresses and criminal records and we might be more accomodating. We will then know where to send the bills for all the damage. Basically, guests do very little to instill trust and the AirBnb booking system doesn't even allow hosts to see whether you might be trustworthy - or not.
Hosts do have some great houses and we have respect. We expect our visitors will have the same respect but experience shows that they don't.
When you all grow up and you get your own places, feel free to hand over the keys to a bunch of complete strangers and let them party without you being there. Evidently in this thread even your parents won't allow parties. Those people are close to you and give you little leeway, why should hosts as complete strangers give you keys to their houses and let you party?
I'm sure its very difficult, but the level of trust required to allow you to use one of our homes as a party venue is normally only extended to our children and their friends - and that often with reservations.
Stella reviews, a bonded deposit and nothing less than respectful replys will get you any where near a booking.
You've all read about the AirBnb houses wrecked by partygoers yes? So have we.