That's exactly the point I'm making. You don't need to own every champ. But WHY is that the case? Why can you get away with never having certain champions in your lineup pool? Because many champions are just carbon copies of each other.
Well yes, the fact that the laning meta is so set in stone. The fact that having a scaling AP system means you can't have champions that vary in power at different stages of the game because you will end up with an even bigger snowballfest. Can you honestly say League champions are hugely diverse in their skillset and utility?
I addressed exactly that in my previous post: you don't need to master every champion to play the game for fun, but if you want to play the game at a pro level, you do. Similarly, you don't need to hit every free throw to play basketball for fun, but if you want to play it professionally, you should.
Now to encompass the other half of your post and also preceding posts regarding Riot attempting to enforce a meta:
That's the ironic thing. Riot attempted to enforce a meta yet it backfired on them. Their attempts to force players to play a certain way actually enabled a greater variety of playstyle. Lane swaps became part of the meta despite Riot's best attempts to reverse that and in the most recent changes, they have accepted that as reality and eased the previous changes attempting to address it. The lane swap itself has evolved to become far more complex than any of the 1/2/1 standard laning could boast.
"The fact that having a scaling AP system means you can't have champions that vary in power at different stages of the game"
This statement is just 100% wrong and misinformed. Consider the recent OGN Finals Najin Black Shield vs. Samsung Galaxy Blue where they ran an Irelia top lane. That is a perfect example of a champion that has ONE and only one power spike and in order to capitalize on that, it is crucial that you do not fall behind and miss that power spike. There is plenty of room for champions that have different power spikes, for compositions that have different power spikes, champions and compositions that excel at various things. To say otherwise when it has repeatedly been proven to be diverse is just false.
I feel like these arguments are being made by reading on paper what Riot is doing without considering what the actual effects are. The game and the environment is far too complex for that. If you want to enjoy the game itself, you need to immerse yourself in it: play it, watch it, analyze it, discuss it, etc. If you are not already, I highly recommend watching OGN. You can do so at twitch.tv/ongamenet
The strategies and plays are very high in the Korean region and the casters (namely MonteCristo) are well-equipped to break down and analyze the deeper meanings behind the map movements. It should address your concerns far better than any post that any of us can make.