Manifesto
There is a problem with your reasoning.
You say no one is forced to do anything.
Say you have some ambitious alliance mates, and you all want to reach the top 50 or top 20.
On the way there you will reach a skilled alliance that likes to fill the stronghold and use a bunch of good troop cards. And no you can be the best Dominations players in the world, that will not save you from the time tie breaker going to their favour.
You can't get those same troop cards for free and win the match for free, basically the point that you missed from the previous poster.
Thus, you are forced to buy troop cards.
That is, by definition, pay to win.