Was just wondering how come if a account is permabanned it can still log into the website?

Also, many permabanned players look to post here to get more information on their bans. For example, Riot used to (still does?) send out different types of permabans by different year codes. People would come in and be like "Yo, I was banned until 2103", or something, and as it turns out, they just have a chargeback issue which can be resolved and the suspension lifted.

Game access and site access are two separate things tied to one account. I assume this is so that you can still log into and use Player Support if something happens to your account mainly, with forum access being a bonus.