Is This Why Some Riders Fear the Rain? [Video]
Center lines, pedestrian crossing markings and similar things are to be avoided at all costs, as they're probably the shortest way to a wipeout. However, as slippery as the asphalt becomes when wet, it certainly does not turn into a hockey rink and neither does it become covered in butter.
So really, a careful rider with minimal skills has no reason to go down. Again, at least not as silly as this one.
As for beginning riders (which seems to be the case here, by the way), exercising on closed roads or parking lots in wet conditions is truly helpful for both throttle and steering coordination and learning more about the grip limit. Add in some more awareness and silly crashes like this one will be a much rare “treat”.