There are many different types of games. There are also many ways to define difficulty.
If characters can achieve any reasonable goal and the question is not if they will succeed, but is they are willing to accept the cost and consequences - is the game difficult, or not? Or if a well build character beats nearly all in-game challenges without much trouble, but one that is unoptimized can't do it - is the game difficult?
The playstyle I like the most works well with quite high difficulty, but also a lot of player agency and interesting consequences of failure. That is, players can't expect to succeed every time without consequences, but the failures lead to interesting complications, not game-stoppers, and it is possible to push towards success by accepting some painful consequences. We want the play to focus on choice and story - and there is no interesting story without a meaningful conflict.
Another style I also like focuses on tactics. If the players cooperate efficiently and use the resources at hand, while staying within the bounds of the genre, they should win. If they don't, they should lose. It is possible to achieve a string of flawless victories (not "no HP lost" flawless, but "lost nothing of value" flawless), but it is also easy to get beaten or outsmarted, if one plays poorly.
If characters can achieve any reasonable goal and the question is not if they will succeed, but is they are willing to accept the cost and consequences - is the game difficult, or not? Or if a well build character beats nearly all in-game challenges without much trouble, but one that is unoptimized can't do it - is the game difficult?
The playstyle I like the most works well with quite high difficulty, but also a lot of player agency and interesting consequences of failure. That is, players can't expect to succeed every time without consequences, but the failures lead to interesting complications, not game-stoppers, and it is possible to push towards success by accepting some painful consequences. We want the play to focus on choice and story - and there is no interesting story without a meaningful conflict.
Another style I also like focuses on tactics. If the players cooperate efficiently and use the resources at hand, while staying within the bounds of the genre, they should win. If they don't, they should lose. It is possible to achieve a string of flawless victories (not "no HP lost" flawless, but "lost nothing of value" flawless), but it is also easy to get beaten or outsmarted, if one plays poorly.