Orb of Fusing doesn't stop at max links for 4 link

Not sure if this is a bug, but I've encountered this multiple times where an item is 4-linked and using a fusing on it rerolls the links.

Is this working as intended? If so, why does it stop at a 6 link?

I assume the reasoning is that it is pretty unlikely that someone would intentionally break a six-link, and it takes longer to roll one so you’re more likely to roll over it by accident.

I know that I’ve bought four-linked boots before and intentionally broken them. A recent example is one of my summoners jamming Hatred and Clarity into the same item and wanting Hatred to be supported by Generosity, but the Clarity to apply to my character.