Hearthstone is an especially great value if you're comparing it to traditional TCGs. The cost to play something like Magic The Gathering is absurd, but you can play Hearthstone for free if you want to.
There are huge tournaments every month, a huge twitch scene, etc
Its a legit game and most people know what they are getting into.
DBZ Dokkan battle on the other hand....
Tournaments or a huge Twitch scene don't make it legit or not. They tell us something about a game's size or impact.
Small (indie) games can be loads of fun. I had more fun with a simple game like Airmash [1] than I ever had in WoW because that game is fair, and you need skill. You can't grind towards an advantage. If you did, you can lose it very quickly. Evens playing field.
Blizzard games, with the exception of Starcraft II, are made for carebears with too much time who want to feel good beating players who put less time in the game not by becoming better (as games used to work) but by getting better gear/equipment/cards/characters. A dog eat dog world, essentially. I've learned and adapted to find that evil.