A crooked chanline and frame flex will not cause ramps and pins to come into play because they're on the side of the ring and cog where no amount of crookedness and flex can make the chain touch them.
You brought up shifting in a discussion of single speeds in #21. You seem to think that misalignment of the ring and cog will cause the chain to react the same way it does to a derailer pushing it to the side an equal amount and it won't. None of my single speeds or fixed gears have ever dropped a chain, and I attribute that to paying attention to chain tension more than anything else. I've never used a tensioner and I never will.