Why do external HDD enclosures have capacity limits listed?

I have never bothered to try to find this out. I am shopping for replacement HDD enclosures that can be used with my router for a large-capacity network drive. The only question I have is why do Manufacturers specify that enclosures have limits on the capacity of the HDD used in them? For example, one model may advertised as supporting drives up to 2TB while another is advertised as supporting 4TB and another 6TB? Is it a limitation of the power supply used or is it a limitation of the controller? Or is it something else? Windows 10 doesn't care when it comes to the capacity of any external drives on the market today.

topgundcp said:

Here's some info:
HDD external enclosures and capacity limit - Hard Drives - Storage

From the link: "That said, if an enclosure supports 3TB (48-bit LBA), then it should also support 4TB and beyond."

That is my thought too. No manufacturer is going to intentionally limit the capacity of his product (an enclosure) unless he is using parts that limit capacity for reasons not relating to the host computer's OS. It's crazy.