@Gail226 Private hateful messages from a host are most certainly unacceptable. Some people in this world are just nasty or mentally unstable, and there's going to inevitably be some of those who are hosts and some who are guests. One poor host who posted here had a guest in the private room she rents in her home completely trash her whole house when she was out, throw things all over, spilling stuff all over the floors and carpets, emptying trash cans all over the living room, then took photos of it all to prove to Airbnb that the place was a disaster and demand a refund. The host was appalled that anyone would do such a thing, as would we all be.
Yes, the pressure on hosts to maintain a 5* average is ridiculous and unfair and also unfair to the guests, as most know nothing about this. I've had guests, when I told them how Airbnb rates hosts, be shocked and say they feel really bad, because they had given a couple places they stayed a 4* rating, thinking it was good- they liked the place and the host and would book there again, they had no complaints about the place and certainly didn't intend to damage the host's rating. They were upset that Airbnb leads them to think a 4* rating is good, they felt lied to.
I'd say a 4* rating was justified in your case of the place not having working heat. Must have been pretty uncomfortably chilly, no way to relax in there on your holiday.
Not using the oven might be another story- if a host does or does not allow use of the kitchen, or only allows it for light meals, or making a sandwich, that should be clear in their listing description. If it's not, the host is at fault, but often guests fail to fully read the description, the amenities list or "other things to note". Guests who make a bunch of demands for special exceptions in their pre-arrival messages are a red flag- entitled attitude, but there's nothing wrong with a guest sending a message like "I see you only allow kitchen usage for light meals, but being as it will be Thanksgiving, we would so much appreciate being able to use the oven to roast a turkey- you'd be welcome to join us or we could make you a to-go plate. I promise to clean the oven after. Please let me know if you'd be amenable to this, thank you." I don't imagine any sane host would take offense to this request, whether they were willing to accept it or not.
BTW, a guest can flag a host as well. If I were a guest and got an unwarranted hateful message from a host, ( a not 5* rating isn't grounds for that, a guest trashing the house or throwing an out-of-control party might be) I'd report it to Airbnb.
