@Qte0
I understand your points and I also understand your frustrations not being able to book places due to not having reviews. However, you are basing these views also on the type of guest you are, e.g. one who has uploaded a profile photo, info, Govt ID etc. and sends a nice introductory message to the host.
Unfortunately, many, many guests do none of this and that, in my experience, is especially true of first time users. Often, they simply don't realise that these things can be important to a host who is opening up their home to a stranger. Sure, all hosts are taking risks by Airbnbing their properties, but I don't think you can fault them for trying to minimise those risks where they can and, signing up a host does not mean we have to relinquish all control of our homes!
So, I have no problem hosting first time users. I have hosted hundreds of them. Most have been great. Like others have said, I will base my decision more on the communication I have with the guest and it is important to have this communication to avoid misunderstandings, especially because unfortunately a lot of guests simply do not read the listing properly.
Still, I have every single box ticked on the Instant Booking restrictions, including that the guest must have a previous review. That doesn't mean I won't accept that first time user, but they must contact me first and can't simply go ahead and book with zero communication. This has saved me from a lot of headaches, believe me, and I am sure has saved some guests from booking my place when it wasn't suitable for them. Right now I have an on-going enquiry with a first time guest who has no idea how Airbnb works, especially in terms of payments, refunds etc. I'm glad that I can answer all these questions BEFORE she books so there are no misunderstandings down the line.
Just because a host is careful (and really most of us should probably be MORE careful than less), that doesn't mean they will be less welcoming to their guests or a bad host. I agree though that I would never turn away a guest just because they have no reviews. It just means I probably need to ask them more questions.
PS Just because you don't leave a review for a host, that does not mean they can't leave one for you, although leaving one yourself could certainly encourage them to do the same.