I'm going to post this LoL game here. Go look at it and pay close attention to everyone KDA.
As you can see the kill spread on the blue team is pretty even with both main carries (mid and adc) having a high score. It could have been nicer with the top and jungler having some more kills too ofc however that wasn't needed.
If you look at the other team you can easily see that 1 player has pretty much all the kills on their team. And if you look at the gold she is like ~3K-5K gold ahead of everyone else on her own team.
This brings up a problem. if all the kills go to one person (accidentally or deliberately doesn't matter for the game. so having a 1 shot assassin like the red team can make things complicated) all the gold goes to one person. And this can be a huge problem, which can lead to a loss depending on several factors:
1. type of the champion
some champions have great early game damage other great late game damage. an assassin type can make use of the gold if they can get close to the dangerous targets. depending on the snowballing of the champion it could be good if you can end the game quickly with it if you can't people will catch up. however getting more gold on certain snowballing champs won't really matter after a while, because they already are snowballing and after a while they reach a point that getting more damage and gold won't increase the time they kill someone.
(e.g. if Loki can assassinate someone squishy (normally a key member) in one 1&3 combo getting more gold on the loki won't matter unless he could reach a point in which he can drop a spell (I know I made an unrealistic example) the only reason he wants more gold is to keep this combo of one shotting someone intact). A snowballing champ always goes quadratic. he will become very dangerous with some kills however in late game even if snowballing he can fall of hard.
Having a lot of gold is nice however if you have all the gold from your team and get killed first the teamfight is pretty much a guaranteed loss. not only because of the bounty gold. the biggest reason is that you do all the damage on the team and the others don't. Why don't they do damage? because they don't have the gold from their items.
following up on the last point if you go alone 1v5 or decide to split push you will draw the attention of at least 2 persons however the enemy team can start an engagement on your team 3v4 as they can be stronger if the game goes fairly even.
So yeah hoarding all the kills doesn't need to be a good thing.