I think the snowballing is from the new stat gain

The new stat system makes the game less snowbally early-mid but it starts to change around level 11 or so. Level 10 is the breakpoint between the old static gains and the new dynamic gains. After that, you're gaining more stats per level than before 4.20.

So what this means is even though level leads matter less before level 10, they now matter more after level 10. So the snowball is delayed and rolls in much harder if you do not close the level gap.

I'm not sure how I feel about this but I believe this is the real reason the game feels more snowbally now. I've had plenty of games where the team with more dragons was losing every fight. The dragon bonuses naturally scale off advantages you have. If you are behind they don't matter.

My advice is, don't get discouraged if you're behind early game. With some decent teamfights you might be able to close the level gap before the snowballing really takes effect.