> Can all orbits be completely filled at once, though? They’ll intersect

Correct. I wasn’t proposing a realistic configuration. Just showing why OP’s visual doesn’t work for the numbers it gives. (It 1D space fills. I expand that to 2 and 3D.)

Millions of satellites is currently accepted as the maximum carrying capacity of LEO before collisions becomes a PITA.

Can't take advantage of the 3D-ness when you want them all to be in terminator-following SSOs. Best you get is 2D, and with current safety margins, even that fills up fast.

However, this was not the point of the illustration, which is more "if you can do this at all, you can do better".