The internet is a part of normal daily life - yours included - so it only makes sense to make it a part of a mission in which you want to mimic normal daily life.
Obviously, I said nothing about Japanese porn or alcohol.
Realistically, those things are probably going to be part of the mix anyway. If you don’t realize that at least one flash drive with porn on it would likely make a 17-month trip with half a dozen guys, internet access or no, then you’re kidding yourself.
As far as alcohol is concerned, Russians on long space flights on the ISS already consume it.