[sparkie]

Middle ground exists because it is ultimately for a court to decide whether or not something is a copyright violation. These things aren't black and white. A license is a piece of legal advice which suggests the decision a court might make if it were to be taken to one, based on past judicial decisions. When it comes to new technologies and new distribution methods (or distribution loopholes), there's not much precedent to go off. The uncertainty here is the middle ground.

[WhatIsDukkha]

You are focused on enforcement which (might be interesting in an internet lawyering way) is irrelevant if noone uses the codebases in the first place because of the license makes it unuseful for users and coders.

Almost all of these "middle ground" license cannot be combined with the normal licenses that have huge functioning communities.