There are two issues. First, there are a limited number of fan headers on any motherboard. Second, each fan header can only handle so much power draw. Typically, fan headers are rated fro a max draw of 1 amp. Large and powerful fans can exceed that limit. The limit can also be exceed if multiple not so powerful fans are connected to the same header by a splitter or splitters.
The Silverstone block I referenced in the link transcends this current draw limitation because the block is powered by a SATA connector coming from the PSU. The tach and PWM wires still go to a PWM header on the motherboard so that you still can monitor and control the speed of the fans. What you can't do with the Silverstone block is control the speed of each individual fan. They will all be running at the same speed because the RPMs are being controlled from that one motherboard fan header.
If you really need to control individual fan speed then you would want to go with a drive bay controller. These are powered of the PSU as well and have pin outs for each individual fan and a speed controller for each individual fan. They come in "analog" (speed is controlled by turning a knob that adjusts the voltage) (e.g.
https://www.amazon.com/YueYueZou®-S...82860671&sr=1-6&keywords=fan+speed+controller) or digital versions that digitally control the voltage (e.g.
https://www.amazon.com/NZXT-5-4-Inc...82860671&sr=1-2&keywords=fan+speed+controller). Neither of these use PWM as the fan speed control mechanism but use voltage variation instead. However, PWM four wire fans can be used on either.
PWM (Pusle Width Modulation) controls fan speed by sending short bursts of electrical power to the fan. The longer the duration (width) of the pulses the faster the fan will turn. The adjustment is in controlling the width or duration of the pulses. The advantage of PWM control is that it allows you to run the fan at lower speeds than you could with voltage control. The voltage is always the full amount but it comes in bursts whose lengths can be varied so the "stall speed" of the fan is considerably lower than it would be with voltage control. The disadvantage of PWM is that it doesn't scale well in bios. Setting the PWM "speed" to 60% doesn't mean you will reduce the fan speed by 40% necessarily. You really have to tinker with PWM to get it like you want it.
Voltage-based controllers allow for more granular control of the fan speed but only allow you to go so low before he fan stalls out because of impedance.
Personally, I have opted for the Sunbeam Rheobus Extreme analog controller but what is best for you will depend on what effect you want to achieve and also the fans you choose. My water cooling radiator has three powerful fans that draw more than 1 amp apiece and I like the granular control the Sunbeam affords.
Hope this helps.