PSA: Snowballing keeps League of Legends from being a boring farmfest.
Rather than writing up a long-winded explanation, I'll just tl;dr it: snowballing is good because it means playing aggressively and interacting with your opponent can more rewarding than playing a snorefest farm game. If you don't reward aggression, there's no reason to be aggressive, which pushes the game meta more towards an LCK-style farmfest while invalidating your LPL-style bloodbaths. Snowballing also allows early game champions to win against lategame scaling, allowing for more variety in viable champion design.
Basically, ideal play involves playing to best risk/reward. Snowballing allows aggressive play to be ideal play in certain situations, which is good for the game.
vs
= Most boring lane ever
or your mom!