Why do you say an observation hive does not have the resources to rear quality queens? We have one observation hive and I'm still learning the differences between managing an OB hive and a traditional hive.
There needs to be an abundance of young bees to produce copious amounts of royal jelly and wax. Most cell builders are 2 or 3 deeps. I only did a quick look, but the only thing I found that talked about minimum resource was 8 frames thickly covered with bees for a small amount of cells. Most observation hive (and nucs for that matter) have far less than that.
A queen-raising colony should be vigorous and have a lot of young bees at age suitable for feeding larvae and constructing queen cells, that is between 5 and 20 day old bees. A single hive body is used when only a small number of queen cells are to be raised, and should have at minimum eight combs thickly covered with bees. Weak colonies produce inferior queens and are unsuitable for queen raising.
Just because they CAN raise a queen doesn't make it a good quality queen. Bees will attempt to raise a queen from drone eggs if given no other choice.
You can successfully walk across an Interstate every day of your life, but it surely doesn't mean you will live a long productive life :-P
I'll stick with my premise that the true quality of a queen doesn't become evident until Fall/Winter when the poor queens fail, which coincidentally is the worse time for it to happen. I'll even be bold enough to say successful supercedure/emergency queens are not as common in feral hives as people think they are.