The numbers are weird, but I think a lot of the "omg so much rubberbands" from casters and shit is due to actually seeing the numbers at the end of the fight rather than the new system.
If the networth difference between 2 teams is huge though, you do get a fuckton of gold. Basically if your team's networth is half or less than the enemy team, you get the maximum bonus, which is victim's networth*0.03 to 0.05(depends on how many people in range, .03 is for 5people) which is quite a lot if their networth is like 20k(600gold for 5person) on top of the 4*victim level so generally 80ish and the 10base, leading to 700g for your entire team for that single kill.
However if the teams aren't that far ahead, and half networth is pretty fucking far, the swings aren't nearly as bad. Say a team has 75% of the other team's gold, following the same situation, you add a factor of 0.33 to the victim's networth, which in this case makes the 20k into 6.66k, leading to only 200g for the kill for everyone from that, plus the rest. It's still more than the old system, however the streak bounty was also massively nerfed, in 6.81 you could sometimes kill someone with a streak and get like 1200g total while now the max streak is 480, so the gold is a lot more spread.
But yeah like I even in the old system, if you got 2 decent teamfights back to back in lategame and got a few streaks bonus gold, you could swing 10k networth. But it wasn't as visibile or as precise as the new UI telling you exactly how much people gained so maybe people didn't notice?