to stop other roles from abusing it
Actually, unlike Tier 1 and 2, this time it's to prevent Supports from abusing it.
When a player collects stacked waves in late, it bounces back. There is a safe collecting area on each side, players shouldn't go alone further than T1's ruins if they only intend to farm so people aware of that let the waves slowpush to them as much as possible to collect everything in one go in a safe position. If you take a wave attacking a tower (or about to and nobody's coming), that's ok, they forgot to defend and you replace them. The countermeasure on support items will still allow you to get full gold from that.
If you just take waves out of that situation, not only you deprive someone of the wave, but you also prevent him to farm any subsequent wave until it goes aaaaaaaall the way to the other side and bounces aaaaaaaaall the way back to your tower.
I've seen a lot of Supports do that during this season, more than during any other, and that puts their mates behind for no real reason. That's something you can't see if you don't think it through, but it's harming the team a lot and I'm glad they chose to tune it down, that's discouraging it without having players to fully understand it.