Shemeska
Adventurer
I knew they received so many each month, that responding, individually, to each was just not feasible.
It just strikes me as something that could be improved to keep people invested and ensure they keep submitting ideas. Both magazines managed to give responses when they were still in print, even if just a form rejection letter. But often some of the ideas I had rejected (by multiple editors) were given reasons for the rejection and suggestions for refining the ideas, to submit it again in a few months and see if it fit the schedule more, or ideas on topics to focus submissions on that might be on the horizon.
Kobold Quarterly manages to give responses as well in my experience, and I presume they're running on a smaller staff than WotC does for their own 'zine.
Perhaps they're really really understaffed and can't respond, even with a form rejection letter. But I can't imagine the number of queries now to be that much more than when the magazines were still in print form and openly recognized as the way to break into the industry. With no physical product, I would actually think it would have less queries. Again, my perception only.