I would argue that difference is that entering my group chat is the same as entering my house to install a listening device. If there is a warrant to tap someone's phone, that is based on probable cause not blanket surveillance. We don't shut down a bar just because some criminals hang out there.

Also, warrants are when there is evidence to suggest guilt. You are not known to be guilty. That is the point of the warrant, to collect more evidence to prove guilt.