You don't need a hub with a physical box. They make splitters exactly like the one you originally linked that simply has one more connector (molex or sata power).
For example:
The way it works is that all the fans get power and ground directly from the power connector, and the motherboard fan header does nothing except provide a PWM signal to all 4 fans, and receive a fan tachometer feedback from one specific fan from one dedicated 'master' fan connector. That way it will never overload your motherboard header no matter how many fans you connected. The PWM signal is high impedance, won't be overloaded, and doesn't get damaged. As long as you don't accidentally daisy chain the tachometer feedback signal, you could daisy-chain 100 fans this way accross 33 of these splitters daisy-chained together and not overload one motherboard header. You can't damage anything by accidentally daisy-chaining the fan tachometer wire, it just won't work properly if it receives competing fan RPM signals. Only thing you have to worry about is that each 4 fans don't overload each sata power connector. Molex has a higher power rating than sata, so if you find one of these splitters with molex power input, even better.
Like this, except less ugly?
It is completely illogical that 'unpowered' hubs or splitters even exist, and completely illogical that so many are ugly big boxes for no apparent reason. The great thing about PWM fans is that they only require 4 wires, and 2 of those wires can come directly from your PSU. There is no extra circuitry needed. It only requires wires and connectors. There is no rule that 4 wires need to go to an ugly box and have a circuit board. Those hubs are just big, ugly, and more expensive for no reason.
