Water in the fuse box???
There is only one fuse, it is an ATO style,,, and not very susceptible to issues with water.. Secondly...It is the main power fuse,,, should have been other issues if that fuse was corroded to the point your having ignition problems.
third... Why did they change the stator??? What led the shop to believe it was bad??
Ohh, what the heck,, disregard all.. You took it to a shop,,, they did stuff, told you it was the fuse, you asked a question...
To answer directly. No it’s not a common fault,,, I pressure wash my bike after every ride. I have had my bike under water in creek crossings up to the seat…, found the bottom on silt filled ponds up to the seat.. Never had an issue with the one single fuse being wet and causing a problem.