Why is champion rental still a thing on shards?

Due to champion unlocks being handled entirely via BE and shards now, there's NEVER any reason to waste a shard on a rental. None whatsoever, making it completely pointless at best.

If you rent a champion and like them, congratulations. You're now out the 40% discount off that champ you would've gotten from the shard you just spent.

If you don't like the champion, congratulations, you're now out whatever essence that shard would've given towards another champion.

Seriously, there's no reason for the rental feature to exist anymore. Hell, there was barely a reason for it to exist before BE.