Riot unloaded a ton of changes. Here's the quick overview:
1). Dragons are the entire game now. 4th elemental dragon buff matters, A LOT. All dragons give good combat stats.
2). The decisions a jungler makes carries a lot more weight now than it did before. The consequences are higher.
Put 1 and 2 together, and you have a recipe for disaster when your jungler is the player that gets auto filled.
It's a lot easier to fall behind experience-wise in the jungle now.
You need to know your match ups and know the fights you can and can't take.
You need to know how to path.
You need to know when to gank and when to farm.
Knowing how to smite objectives.
If you do not know how to do these things, then it will NOT be difficult for you to suddenly see yourself 2 to 3 levels behind the enemy jungler.
And in a game where dragons can make all the difference, smite levels matter.
If Riot is going to place so much weight on an aspect of the game that is so heavily influenced by the jungler, then they should remove the possibility for players to get autofilled to jungle in solo queue. I don't care if my mid/top/adc/support has only played the role two times before in their whole life. It's manageable. You can still hard carry. But if my jungler doesn't have a single clue about what he's doing, then my ability to influence the game (as any other role) will fall dramatically.