Here I would like to also mention RawTherapee, also open-source, together with Darktable (with is more newb friendly) they are great software worth to spread.
On top of that, developing for photo, video and audio is hard due to all the maths involved. The amount of brains capable of that wizardry is finite, the amount of brains able to do open source work in that field is even less, and other FOSS projects compete heavily for these brains.
Yup, that is a massive factor as well. My go-to example is OpenStack. It's incredibly powerful and malleable, but it shows on every corner that it is built by university nerds for university nerds - you either need to have a massive amount of highly educated manpower to deploy it, or you need to have a source of cheap or free labor where you don't have to pay for the onboarding time.