Spellthief's edge tribute is inconsistent

Hey there. Support main since season 4. With brand support becoming more present in bot lane I found that spellthief's edge is pretty inconsistent when it comes to the tribute passive.

When Brand has spellthiefs and uses a single ability on ONE enemy, he gets all three gold tribute stacks from his passive. However, when I play Nami and my W bounces between enemy champions, I only get one stack of tribute gold. Same goes for Sona. I can hit two enemies with my q but only get one stack of tribute gold.

It makes it pretty easy for brand to rack up on that spell thief gold compared to other supports. Any thoughts or comments? I personally think this should be fixed to make it more consistent between champions.