I don't think it particularly suffers from not having "good defaults", because it doesn't get adopted by word of mouth. And people are not shopping around The Best OS that they find, and sadly, they evaluate that Linux just doesn't have the juice.
Two things here.
One, OSs get adopted because of the package they arrive in. Laptops have Windows bundled, schools get computers with Windows on the cheap. Phones come with whatever they are integrated - often, not even a major upgrade is possible on them, let alone an alternative OS.
In my opinion, products like the Steam Deck are what get Linux adopted. They provide excellent functionality out of the box.
Two, PCs in this age thrive on interaction. Overwhelmingly, they are bought to interact with other PCs, either directly by network or through formats of specific software, like docx. Therefore, the functionality depends on how well they can participate in a network. This is where Microsoft really made it big with how ruthlessly they pushed Windows as an app platform and Office as the productivity software baseline.
Hence, in the end, what makes Linux really competitive today is the proliferation of web apps, because Linux has first class browsers, and the existence of Wine and its related software. Take these two away and the OS is not even talked about as an alternative to anything, just a specialty, or a curiosity.
Really, an alternative OS can do two things. It can either set the trend, which is not very likely, given that we are talking about alternatives. Or it can follow the trend, or "embrace" it, in MS lingo.