I've been daily driving linux for years now and here are the things i can think of:
- awful software distribution, especially for proprietary
- corpo tranimals running every project, making it subject to die overnight out of nowhere(just like the devs)
- insane defaults everywhere, often not following any standards at all
- the "customization" that's often advertised is massively exaggerated, instead of having 100 different choices for each part of the system, realistically you get like 2-5 at most with even less being of high quality, which is even debatable
I wonder if those things could be fixed without just sitting down and writing mountains of code alone