This is useful if the machine you're looking at isn't given specifications, or is broken and you want to know what model it is. For example, if you are looking to buy a used MacBook on eBay, but the seller didn't provide the specs because they don't have a charger or something, you can quickly find out what that model was by using the serial number. I use everymac a lot too, but both methods are useful.
Here's hoping there is still some way for the serial to identify what
model it is, just not the other info that is apparently bad to know.