The main thing with db0 as opposed to other instances is that it:

a) also caters to another crowd (FOSS enthusiasts)

b) doesn’t suffer (at least from whay I’ve seen) from censorship problems. Db0, the owner, isn’t auth far left (tankie) but anarchist and seems pretty reasonable.

c) Actually has a sign-up process (which means fewer people choose it)

d) Has a lot of big comms in software due to early arrival and not doing stupid things.

I myself have an acc there, mostly due to foss interest.