Not everyone may know this, and it may not be obvious. Once you have a .Win account on one sub, you can use the same account on all .Win subs.
If you have an account on one .Win sub, just log-in with the same log-in info on another .Win sub. You don't have to make an account more than once.
I know it is weird that (as far I know) you are not automatically logged-in on other .Win subs when logged-in on one of them. In a sense they are basically websites of their own while also being able to share accounts some how.
EDIT: Ofcourse you should make sure you only do this with Official .Win subs, which you can find a list of here.
Though it may be wiser to maintain different usernames on different sites anyway.
Why is that?
As Reddit showed so prominently, a favorite technique to prevent rational discourse is to attack the person instead of the argument. ("You post on T_D therefore your argument is invalid", or just mass-banning anyone posting on a sub you don't like.) This is partly why they desperately try to avoid anonymity in general, and why they like to make account creation as difficult as possible.
The less history you have, the less likely it is that someone can find something in your past to attack.
Why do you care what a deranged lunatic that judges your message based on your post history has to say, or thinks about you? Isn't that just a filter for those lunatics?
I don't.
I do care about otherwise-moderates who never see an argument because it got brigaded (or banned) over post history.