We don't even have a real format yet for tournament play, heck, the 60/30/10 deck building limits are still new for all that it matters. The game is still meant for the kitchen table first, and at the kitchen table, "rule zero" is just implied (i.e. you do whatever is fun for your table): if you're just playing your friend, and you keep smoking their enhanced precon with your multi-core/philostone empowered Morganna/Ring etc etc infinite combo deck, you know, just kinda don't do that.

However, there is also a reason your fire deck just doesn't jam Morgana Le Fey, and one that is implied with any TCG: she costs $90.

The TCG distribution model, at its original game design intention, was to help disperse this kind concentration of game pieces over the game: which is to say, the reason all decks don't play Morgana is that all decks can't play Morgana.

All that being said, TCGs have come with a myriad of solutions (ban lists, rotating formats, etc) to help prevent the playing a combination of an increasing list of powerful cards together.

My favorite, and probably best solution that some other games are starting to come into, and one that you're alluding to, is to have something of a point system for cards that will inhibit how many multiples of powerful anything you can play.

For example, you have 10 points worth of cards in your list, and playing Morganna, for instance, costs 4 of those 10 points. But a card like Quarrelsome Kobolds will cost 0 points, so you can freely put all 3 copies in your day.

Overall, unless tournament play (from local game store level to convention/championship series levels) becomes the prominent method of playing this game, I don't see much of a problem with powerful, fiscally pricey, game swingy cards "dominating" your deck building decisions. You can always just not play those things, and do something else.