Roommates: Are Notices to Co-Tenants Applicable to All Tenants

I have been told that co-tenants are considered one entity. That when one person gives notice it applies to everyone just as if one person gets evicted for noise everyone gets evicted. There was a specific instance where a friend got evicted with his roommate for noise and the apartment manager, knowing the situation, allowed him to reapply for a different spot alone. They did it that way because, as co-tenants, it was considered an all-or-nothing deal.

Is this not the case? Is there an exception in when rent control laws apply?

Roommates: Are Notices to Co-Tenants Applicable to All Tenants