That's usually balanced more by banning or restricting a card than by rarity. It may have been part of Garfield's early design to use card rarity to limit the meta but it simply doesn't work (instead of limiting the cards it would limit the competitive players to those who can afford the cards). Instead there are multiple formats with different sets of permissible cards, from the most permissible (vintage, which gives access to any card that has ever been printed and is not banned or restricted to 1 copy per deck) to the least (standard, which only gives access to cards from the most recently-printed sets). The deeper the card pool, the more expensive the format as those cards are not reprinted due to their gamebreaking power.

And then it was discovered that it is effective tactic to make money. You could sell all cards in the set for 50 or alternatively you could sell bunch of packs mostly filled with filler for 150 and get people buy quite lot of them to chase the limited set of strong and competitive cards.

I thought this is governed by point-buy systems where you have a certain number of points to spend on your deck, and powerful cards just cost more points. Not an MtG player though, and I assume this also varies from play to play.