We might have to debate that TN.
I'm old and I have to protect my knees(especially my right one after a lacrosse injury) and I've trained plenty of clients and teams I coached in weight lifting but I'm old school and preach the 90 degrees. It can depend on how old the person is, other factors and there are a lot of other things to worry about with proper form. I love squatting as it's always been my favorite exercise.
But I'm always open to new ideas.