I'm not sure this is the main cause, but it's an interesting point of view.

For Amazon, their Network effect is huge because they have a huge delivery and storage facility network. The barrier to entry is huge.

For Airbnb, it might be closer to what this article is saying. But also it's less convenient for home owners to have their location on multiple sites (need to sync calendars, the subscription takes much longer...). So they pick one, which is Airbnb.