I'd argue dotcom domain squatting has a big part in the lack of names available. Eventually, most startups that could use them will go bust and sell the domain 5-10 years down the line anyway, it's outliers like google.com that are always going to be taken.

New namespaces like .app should help with the problem, but at the end of the day, the culture itself has a limited namespace.

I've always gotten fairly lucky with .coms for my projects (managed to snag feedsub.com recently, had minfolio.com at one point, etc..), though the ones I've let slip ended up being squatted upon for thousands of dollars because of their potential (I think) branding value, which is a shame because it could've been put to better use since I couldn't follow through with a project.