Well, I don’t think sandbaggers and cheaters are an issue. Anyone that’s seriously competed in a sport will tell you that people enter lower categories all the time. I know a guy (at another sport and in real life) that loses “B” on purpose because he’s scared of moving to “A” and getting his ass handed to him.
Besides, what’s the purpose of racing if it isn’t to win? If you want to train or ride to have fun and sweat, then join a group event.