One of the major points of this guide is to take advantage of 100% Eidolons not being P2W but very much freely obtainable with far less effort than it takes to play through the game to the highest levels. I'm quite sure a far greater number of 100% Eidolons have been obtained freely (especially by re-rolling) than through Star Coin gachas as it's much easier for the vast majority of players to start a few hundred new accounts than to pay for a few hundred Star Coin gachas.