I feel it’s a bit disingenuous to discuss that a developer might pay more for a lot with a house on it, to build more houses, but you don’t really touch on, at all, how much the resulting housing might cost. Surely 20 units on a single lot will be cheaper than the single family house.

Now you have potentially 20 families, or at least 20 individuals, paying taxes, participating in the local economy, etc instead of just one single family. Lots of economic benefits to consider here but saying “downzoning good, actually” because a developer might pay more? Idk. seems pretty poorly thought out.