Why is it against the rules to discuss previous series?

[newspresenter]

Can't work it out, if anything its a good thing.

[Crimson Dynamo]

maybe because this is about BB11?

[Claymores]

Seems a silly rule always, but they've relaxed it a lot this year - Rachel and Mario are forever going on about things from the past.

[psychtracker]

I'd guess at the start (BB2 onwards), maybe they wanted to restrict possible tactical discussion - relating what pple did in previous situations. Also, another reason maybe it doesn't exactly make for great TV...having them speaking ad nauseum about previous seasons.