There are too many people on lakes who don't know what they are doing and you will see them this holiday season especially. There are a lot of people who will be piloting someone else's boat and renters. PWC's are something that gets loaned to a friend who knows nothing of the rules at all.
Before I got my boaters license I at least looked at the rules. My rule for myself was stay as far away from others as possible. I have had my license for years and that rule still applies.

The other people are those who have licenses but don't understand the dynamics of surfing or boarding and don't know that the water needs to stay clean. Then there are the fishermen who figure they own the lake and FU for being out here so I am going to cut across your bow for being on my lake. Not all are like that and they are the exception but they are out there.