Opposing any level of density or capacity beyond single family houses with low lot coverage in your (urban/inner suburban) neighborhood is straight down the middle of any definition of NIMBYism I've seen in recent use. Particularly when you live somewhere that normal-sized houses go for $800k (!).

I'd also (tacitly) oppose large single family homes replacing small single family homes, but that's because I'd prefer to see even larger apartment/condo buildings. When each project is so politically expensive, it's important to get as many new units as possible out of each one. (Looks like defen is on board with this idea).

When two single family homes on a lot is encroaching on a community's threshold for permissible scale, usually a large apartment building would be out of the question. So I'll take what I can get.

At a 2:1 or better multiple (new units : demolished units), these conversions might be decent. You could increase a city's housing stock 2x that way, and it'd be a less drastic change than dozens-hundreds of skyscrapers needed for the same effect.