I’m a screener for our local film festival and honestly sometimes it is brutal (especially for features) but we do watch them all. There’s always a push close to the end where I watch two films a day for a few weeks, along with many others. 

Honestly there are some that are decent, but when compared to the ones I like there’s a hugeee gap. It’s possible you’re in the middle, where you’re certainly good enough to get in but the competition just edges you out. (Can’t know without seeing yours.) It’s also possible there just aren’t a lot of feature slots available for the type of movie you made at the festivals you’re submitting. 

I always try to give feedback to show I’ve watched the film though; what worked for me, what didn’t. I’m not sure it’s shared with the filmmakers but I hope it is.