Because math doesn't matter, but words are cool when you're a writer. Aaargh.
I'm no Flappy champion, but I'm pretty certain there is very little diffuculty-ramping. It's certainly not getting exponentially more difficult.
That said, the game is actually about luck the better you are at it - if you are skilled enough to always get through the gap if your bird starts near the gap, then the difficulty comes down to chance - how far away the gaps are vertically from each other at each step.
That's like saying your chances of rolling another head after rolling 1000 heads are smaller. They're not. It's still 50/50.
Exactly. Unlike other infinite fliers the game doesn't get increasingly harder. The speed, pipe distances and sizes are all constant.