There is this whole culture at DL that believes receiving a complaint is a failure. If you get a complaint you get written up regardless of the validity of the complaint. The corporate logic is that they empower CMs to make guests happy (and I must admit, CMs to have a lot more room to "make things right" at DL than most other places) so when you fail to make a guest happy and they complain, you have made a mistake. I believe this is a DL thing as WDW seems a bit more strict based on what I've experienced and heard. Other local theme parks are also more strict although it can be argued that the different demographics of the visitors may require them to stay on top of things a bit more.
I have a couple stories of how ridiculous from when I worked there. First there was the lead who got written up because a guest complained that he asked her to stop smoking in a dining area. Second, the lead that got written up for cultural sensitivity because he asked guests to stop throwing food at each other and they made up that he used a racial slur (I knew the guy and not only would he never use those words, if he did he'd be smart enough not to use them on stage). Third, a CM and his manager got written up by higher ups (which I also think cost the manager a promotion) because some guests complained that their table had been cleared before they were done eating (a pretty common scam, and part of the reason why River Belle Terrace no longer uses real plates). They refused to give the guests a free meal and couldn't have if they wanted to because the restaurant was not yet open! Of course the complaint got the scammers a free meal and the CMs that stood their ground got disciplined.
Oh and one story I saw as a guest. There were a bunch of people waiting for a pin release in Tomorrowland. The CM announced that they would be forming a line over in one area. This one woman, who was not near the area, decided that instead of getting into line she would start screaming and cursing. Instead of getting kicked out, they let her go in before everyone else in line.