Leech & +Gems Suffix instead of Prefix?

Crafting axes a lot this league it is kind of confusing me why these stats would be prefixes instead of suffix? I mean +gems I can maybe understand it, because it would be broken, but the leech are basically worthless stats as prefixes which actually could be useful as suffix, no?

Did get excited rolling max life leech with a very good hybrid roll only to realise the leech was taking up an important prefix slot, and failed annul.