My best Airbnb experience was my first one 4 years ago, when with a partner I booked a room in a house with the owner living in. We had a tremendous time, we had bbq one night together, it was an enjoyable not planned semi-communal experience. Nowadays, the experience Airbnb offers is mostly that of a poorly managed hotel that has properties all over the world. It can be worthwhile when traveling in groups, but otherwise I tend to prefer hotels.

Still very common. My parents are AirBnB "super hosts" and they live in the basement due to regulatory requirements that are common in pricey American cities.

I think the host caliber was much different then too. The professional AirBNB people had not setup shop.