You disagree, and then what?
How do you want guests to do Instant Book if they have to show their star ratings before?
Airbnb already gives you the option to prevent guests with thumbs downs to book, it's not bad.
Besides, there are for sure some bad guests who still carry 5* everywhere and only positive reviews, it can happen.
Instant Book also means no work to convince people to book your place. So there must be a compromise.
Airbnb can cancel Instant Books without your consent, if the guest has bad records in their system.
It already happened to us. Booking confirmed, and 30 minutes later, canceled.
Airbnb probably avoided us a little nightmare. There wasn't any review, but maybe it was a recreated profile.
If you don't accept a part of risk, you shouldn't do this. Nothing will protect you 100%.
If you attract guests with 1 star ratings, then your listing might have a problem.
There are ways to discourage horrible people from booking your place.
You should treat your guests equally, great or not great. Some will give you more work and worries than others, that's all.
But if they pay more or less the same prices, they must get the same services.
By the way, we didn't really rehabilitate the guest in question.
Although she fell in love with our place and our hospitality, and gave us 5* everywhere, she didn't deserve our full support after we saw how she left our place. Nothing catastrophic though. So she got a mitigated review.
We let customers proving themselves (or not), before assessing them.
If you're a serial complainer (like other participants in this forum), you will draw bad reviews from bad guests.