Can you imagine if everyone paying monthly subscription for any type of software took 10% of their budget and donated to the alternatives? I'd bet that any FOSS project could reach parity to their proprietary counterpart in three years.
Seconded. I don't know much about the code, but on a usability level it sometimes feels even more polished and pleasing to handle than many big proprietary offerings. I would go so far as to say it's one of the best executed desktop programs of the current era.
Just to share one datapoint - I have not looked at the internals myself, but having talked to a couple of devs who has spent a great deal of time working with Blender at a code level, one takeaway seemed to be that there was a lot of code duplication caused by each dev doing their own thing and not having an overall architect to rationalize some parts of the code.
A particular example that was mentioned was the importers that were each done standalone rather than built on a common framework. This was a couple of years ago and of course things may have changed since then.
Just to note that the developers were still extremely positive about working with and in the code, but it does seem plausible that there would be issues like this in a codebase where many devs focus on a small piece of the overall puzzle.
Supporting open source creates competition for your paid alternative, so they're forced to give you a better product or a better deal.