Why are USB hubs provided in 4- and 7-port varieties. What’s special about these numbers? Why don’t I see 3-, 5-, 6-, and 8-port hubs?
Is there something special about 4- and 7-port configurations that makes them more attractive?
Solution:
If you’re tying up one port to only really gain two, why do it? 4 port hubs are common, and an seven port hub is simply a doubled up four port with one port gone because you’re using it to extend the four port again.
It’s cheap manufacturing.