Quite a few small developers in this space. It's not like indie gaming, but there's also less competition. I think you need to be a musician/producer to be successful here though.

The implication seems to be "no".

Steve Duda wrote Serum, probably the most popular synth plugin in modern electronic music. everyone I know has a license. so "yes", with the caveat that it's difficult to actually create products of this level of quality

That implication would be wildly incorrect.

With the operative word being "developers" I disagree.

Yeah but facts don't really care about agreement: there are loads of renowned single-person VST shops, and many more "just a handful of folks" ones. Chris Heinz, Steve Duda, Strezov Sampling, Matt Tytel, heck even Plugin Guru, etc. etc. are all renowned folks in the VST/VSTi world, and that doesn't even scratch the surface.