Your second point is key. In an ideal world, open source could rival and even beat the best paid offerings (see: blender). But in most cases it just doesn’t. There’s not a dedicated team working on the open source products, working with HCI experts and designers on every detail of the product. It doesn’t preclude the open source being better (see, again: blender), but it does push a LOT of workload onto a bunch of hobbyist developers working in their spare time. The resultant burnout is typically why you see these projects sputtering along for years and years. I don’t know how to solve those problems either, but they’re your real “roadblocks”.
I suppose it all comes down to money, Blender is an exception rather than the rule. They get a lot of donations from big companies, so they can afford to have a lot of people working on the project full-time. Most projects don’t have that luxury, so they get stuck like you said.
To be honest, I don’t know if there is a way to solve this, if there is it certainly isn’t easy
