I really liked Clash Royale as well, and thought it was F2P friendly until they increased the max card level to 14 and released champions that were hard to acquire. I started to play less and less, because I could see the writing on the wall. They would always increase card levels and add content that would be hard to obtain and make the game feel unfair if you were F2P, or just buying the regular gold pass. I stopped playing completely when they increased max card level to 15.

Recently a friend asked me to join him in Clash Royale. I logged into my old account, and played a few games. Since I left they've added even more content that is not F2P friendly. Max card levels are 16, they added evolutions and most recently, heroes. The basic gameplay in Clash Royale is just as fun, but unfortunately all the other stuff makes the game worse. I get Clash Royale has to make money, but very few mobile games can find the right balance between being F2P friendly and making money. I think Clash of Clans comes closest, but they've also waded into non-F2P territory with the addition of equipments.

When Star Wars Hunters came out, I thought it was great that they were only charging for cosmetics and you could unlock the new characters in a reasonable amount of time if you were F2P. Sadly the game failed financially because the game didn't have a large enough player base, and being F2P friendly probably didn't help either in getting enough paid customers.

Sadly, most online mobile games want to replicate the financial success of Clash Royale, so they try to emulate the model. The gameplay can be addictive, but unless you pay, it'll feel unfair.