If a game is so hard that the player gives up, they won't buy your next game. That is an existential threat to your game studio.

Worse though, if your game is deemed 'unfair' rather than just 'hard', then even the hardcore gamers will avoid it. That's enough to kill the business before you even start the next game.

Some studios pick the 'hardcore' market, especially once they've built a reputation and a following, but everyone else needs a more general appeal in order to stay in business.