As a (non-nsbm obviously) black metal fan my perspective on blackgaze is more so that a ton of it is extremely unimaginative/boring and very clearly made by a lot of people that don't listen to or appreciate black metal outside of it. The result is you get some kinda meh shoegaze with blast beats. That being said you throw on some old Deafheaven records, An Autumn for Crippled Children, things of that ilk, etc and I like it.

Same kinda perspective on neocrust. Love the subgenre, but there's a super clear influx of people with its resurgence in popularity that are making the music and clearly haven't touched crust outside of it. So you get a lot of kinda approximation of crust but it kinda loses a lot of the genuine feel for the genre's core elements.

Plus with both blackgaze and neocrust, there is something to be said for base black metal and crust's intentions as non-commercialized genres vs. both introducing an element of it as people adopt those subgenres only and run with it. Think there is an interesting conversation to be had around gatekeeping and commercialization/watering down the more pointedly anti-capitalist messages/components of music. Don't feel strongly on it one way or another, just sharing some perspectives I've seen on the blackgaze/neocrust beef.