That's what happens. The more players you got, the more of 'em just aren't worth the time.
There's also this huge push for every play damage classes make to feel gamechanging, and a lot of things are getting stacks. Liss is the most recent to the list, I think...
I don't know what's going on, I think they want games to hit some sort of 18-minute critical mass and turn into one big teamfight that ends the game. It's how it feels, anyway.
All the tools in the game are inherently biased toward the team that's ahead, but mostly because League punishes being behind so much.