have you sent even 1 compliment to UA for something? I have sent 5 complaints to UA this year. only 2 of them were actually about flights (and those weren't really complaints). 1 was about the removal of ability to hold on .bomb, 1 was about the fares not showing taxes included, and 1 was about the problem with UDUs (no CR-1s). my first complaint about my flying experience was about an FA being rude about me using the restroom while the seat belt sign was on (i acknowledged that I should have stayed in my seat, but the FA could have done a much better job of letting me know that the seat belt sign was on). The other time was when a gate agent lied to me about my seat assignment. In both of those emails i made it clear that i didn't want any compensation whatsoever.
Even with 5 complaints in 1 year, I don't really consider that excessive. Especially because I have sent in about 10 or 11 compliments this year. I would imagine the OP has not sent in one compliment, and that's what has really caused them to look into it more.