Feedback's tough. I sometimes sit on content committees for conferences. Sometimes for a given abstract my feedback would be along the lines of "Did you even try?" or "How many different events did you submit this generic abstract to?" But mostly it would be more along the lines of it's OK but there's a known person who is better plugged into this particular topic who also submitted and their abstract is sharper.
Conferences do often try to get new and more diverse speakers but you're still competing with people who do this sort of thing for a living. The bottom line is that a lot of feedback would be along the lines of "You were fine but someone else really grabbed us in one or more ways."
Feedback like "Did you even try" is just as useless as "You were fine but someone else was better." Why not simply state what's wrong with the abstract, and how it could be improved?
Conferences do often try to get new and more diverse speakers but you're still competing with people who do this sort of thing for a living. The bottom line is that a lot of feedback would be along the lines of "You were fine but someone else really grabbed us in one or more ways."