To a certain degree that is correct, off course you can always throw more money at it than you can aquire free diamonds.That´s of course true you don´t actually need money, just diamonds. So yes I could spend my 20k diamonds from the spire get into the gold league and not have to pay actual money, but that argument is the same all over. So using that argument pay2win doesn´t exist, because I can always use free diamonds to win...
But yes since all the changes and generous diamonds payouts pay2win is not really applicable anymore.
I mean I bought some expansions before the change from 2000 diamonds max to the currenty 17500? I bought about 14K diamonds(80 euro) + 2 workers (10 euro) in my life for it. but right now I own 348450 diamonds worth of expansions, own 6 magic workshops and 14 magic residences.
So plenty of free diamonds there, in fact almost all of them are.
So yeah it's not really pay2win anymore. you can easily replace pay with effort these days.
It's just thay paying is quick, and free takes a lot longer but you get there.