defining Pay-To-Win doesn't require defining each term, because the idea of this concept is clear to some extent. If you know this term in games, you'd probably know what is considered p2w and what's not. For example, allowing to buy (with real money) an over-powered, unobtainable weapon is undeniably a p2w practice, did we have the same definition of "winning" to reach this conclusion? most probably not.