It’s actually not the satellites as the bottleneck typically from what I understand, it’s the ground stations that serve those areas getting too congested.
The satellites may not currently be the bottleneck for certain areas, but they definitely don't support anything resembling a densely or even sparsely populated area.
Typical calculations (using only publicly available info as a caveat) generally point towards the current starlink constellation supporting a really low density of antennas.
If you want the details, the person who created starlink.sx has a great blog with some incredible calculations[0]. The section that is most relevant is under the heading "Simulation with TDM and beam spread combined".
Basically, the result is that starlink could support around 15 antennas/user terminals per "cell" at 75mbps, where a cell is about 252 square km. This is roughly 1 terminal per 17 square km.
If you allow for 10x oversubscription, fairly common for ISPs, that gets you to 1 terminal per 1.7 square km. Not really that impressive when you compare it to the density and services where 99.9% of people live, but it clearly helps out the small number of people way out there.
