whoever split Mimulus into diplacus put all of them into this species even though it's apparently now split into several species. This is a good illustration of why that sort of splitting (on the part of taxonomists) can cause harm, especially considering that the papers indicate they hybridize. But in the mean time can we create a subgenus to put these in so they aren't all wrongly ID'ed?

I don't think it is good to make these splits and then arbitrarily put all the observations into one of the species.

See https://www.inaturalist.org/posts/18612-observation-of-the-month-red-sticky-monkeyflower-diplacus-puniceus-phrymaceae and all the links there, for instance.