On my original point about "stages", the part that really got me thinking was that the person who designed that questionnaire probably didn't even give it a second glance. They just wrote it, and it felt fine, because to them it seemed like a normal way of thinking.
Same to your point about there being few events that aren't targetted at couples and families. When people are in a heteronormtive couple or a family, then they won't even notice how the whole world seems to be set up in a way that is tailored just for them. It's perfect for their needs, so why would they see anything deficient with it?