Comment by Jtsummers
3 days ago
Iridium offers lower bandwidth and much larger cells than Starlink. But yes, the number of customers within a cell is also key to why there are so many Starlink satellites. Suburban (let alone urban) population density can easily consume the bandwidth available through one satellite.
Smaller spot beams are still technically possible for an Iridium-like constellation with fewer satellites. That's what e.g. ASTS is doing.
In fact, more than one (or maybe two, for geometric reasons near the equator where polar orbits are sparse etc.) satellite concurrently visible is pointless if the ground station/mobile device isn't also heavily directional, which is not the case for small, quickly moving handheld devices at least.
One other reason for wanting more satellites splitting footprint coverage between them would be if the satellite transmitters were transmit power limited.