No restrictions on fields of endeavor and no discrimination is a pretty basic tenent that goes back a long long time (the DFSG were published in 1997, there are other things saying the same thing that pre-date it).
I also know this is what other open source lawyers are saying as well (in fact, i haven't seen one who believes it is anything else).
I'm sure you can make up another word other than "proprietary" to call it, but ...
As for questions: The main commons clause page makes the claim "Initiated by a coalition of top infrastructure software companies to protect their rights"
Care to list them?
Additionally, even ignoring the significant vagueness in the clause, there are plenty of combinations of licenses with which this clause makes literally no sense. It seems there is no guide or policing of these. Truthfully, this all does not feel well thought out. Who actually participated in the drafting?
Here is one that exists in practice:
neo4j is commons clause + AGPLv3
AGPLv3 section 7: If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term.
...
GPLv3 is identical in this respect, and LGPLv3 is a set of permissions on top of GPLV3 that does not revoke this clause.
This seems to make commons clause incompatible with a lot of software.