The issue is mainly of patient load and time spent per patient. I think because the context with which they do this, they can't afford to pay >$50 per 99213, which makes sense to me. However, anyone who completed residency would know that doing 4 15-min med checks an hour is not very good care. Currently the in-network billing rate for Medicare for 99213+90833 ~ $175, which is somewhat more reasonable--> given a 30% overhead this would yield about $250 per hour. So cut another $50 out you'd get about $200 an hour for 2 30 min med check + "therapy". This is more sustainable.
Ideally, I'd like to do 45 min 99213+90836, plus 30 min 99213+90833. If I can do those with an average pay out of $200 an hour with some admin support (i.e. appointment scheduling, PA requisition, etc) such that all patient calls get routed the other way, then I think it's a job that's worth considering.