Alonso ran straight on at turn one, twice (once when under yellow flags, yet nobody screamed and shouted about that), maybe he lacks spatial awareness or had brain fade...
Yes. Maybe. Didn't already Suzuka imply something like that ;)
But yeah, everyone surely did some mistakes because it was wet, but not everyone crashed. I don't remember Alonso's mistakes, should see those again. But if it was just going wide that isn't a big deal, Grosjean lost it on the paint because he turned too much.
Compare racing lines yourself, if you want.