I submit that the same goes for satellites in orbit. How many 5000+ constellations will there be around the planet before we run into space congestion/traffic and aesthetic problems?
The only reason there is even a point for Starlink to have more than one satellite covering the same geographic footprint simultaneously is that both the satellites and the ground stations use phased array antennas and are largely stationary (or at least are moving somewhat predictably/rotating in space fairly slowly), which allows reusing the same frequency for customers in the same ground cell at the same time from two different satellites.
Highly mobile ground stations will likely continue to be served by a single satellite per ground location for the foreseeable future, which makes spectrum the scarce resource.
I think you underestimate just how big space is.