Why do a minor release when patches are also backwards compatible?

Some of my team members have a habit of releasing new non-breaking functionality under patches. I know that new functionality is supposed to be tagged under a minor release if it is backwards compatible, but I cannot come up with an argument to not use patches if nothing breaks. Our dependency constraints are mostly all using the caret symbol, so running updates will include the changes no matter what. Besides convention, why should we discriminate between a minor release and a patch?