Another thing that can be a problem in today’s high tech/high spec notebooks is powersupply. Often if you use both USB ports, they share the same controller AND often don’t offer full power on both ports when both are in use simultaneously. This is one problem the powered USB hub can solve (especially the better ones), it has it’s own power supply dimensioned in such a way that each port should have access to the full power necessary.
Especially for USB-powered controllers this can be an issue. Obviously not so for controllers that have their own power supply.
On my MacBook (with powered MC6000 controller) I always use a high quality USB hub. I either hook everything up to the hub (most of the time) or use one port for the controller and run everything else off the hub.
I have noticed on previous occassions that hooking up my external SSD or HD together with my controller has caused problematic behaviour from the USB-powered disks. With the USB-hub I don’t have such issues anymore. Everything works as suspected and all necessary LED’s shine brightly.
Just my 2 cents.
Greetinx.