It sure is a weird thing, but yes, the first mobile devices that shipped with USB didn't really know how to charge off it.
Which, to be fair to them, usb was never supposed to be a power delivery standard (at least not more than the 5 volts needed to power a mouse)
And now pretty much all of the portable devices in my house can be charged with 5V/2A USB :D
Had to use a barrel plug to charge it.
Spent a very nervous and sweaty day figuring that out when I bought one used with no warranty or returns and it didn't boot properly =)