Riding into a river isn’t a great idea on an acoustic bike either, of course. The main reason is that you don’t want to be swept away by the current. The secondary reason is that you’ll have to clean and re-pack your bearings etc. (especially axles and bottom bracket) afterwards.
Ebikes should handle rain just fine though (I know mine does). Just don’t ride it into the river.
Riding into a river isn’t a great idea on an acoustic bike either, of course. The main reason is that you don’t want to be swept away by the current. The secondary reason is that you’ll have to clean and re-pack your bearings etc. (especially axles and bottom bracket) afterwards.