Update:

Thank you for your insight and feedback.

The “Mainframes” proposal has been cleared to continue.

Update as of the end of 2018: The proposal never got enough interest and has now been deleted. I personally wouldn't mind seeing some mainframe questions here, but I don't think that's too likely.

^{original post:}

There is a new Mainframes proposal in Area 51 about to undergo a final evaluation to see if it should continue efforts towards becoming a full site:

Mainframes
Proposed Q&A site for people who program, operate and want to learn more about mainframe and mainframe-specific technologies

Please have a look at this proposal and the top example questions. We don't generally split off a subject simply to give a sub-topic its own space, but the audience proposing this site has curiously little participation/overlap with our existing communities.

I'm trying to determine if the proposal audience is largely unaware of sites like Serverfault (and related tech/programming sites) or if they feel these topics might not be a good fit on our other sites (in either subject breadth or culturally). I'm trying to determine the suitability of this subject for sites like Serverfault.

Are the example questions predominantly on topic (and welcome) on Serverfault and related sites? Or should we tap this impressive effort (~2-3 weeks to complete Definition) to create a new community?

Any feedback welcome below. Thank you.