Why is Celeste's difficulty so satisfaying?

I've been playing this game the whole week along with I Wanna Be the Guy remastered version and, comparing both of these games, Celeste just feels different even though you die all the time in both of them. In IWBTG the difficulty feels satisfying when you finally get over the level, but trial and error feels frustrating, while in Celeste this constant diying doesn't feel quite stressfull. What is it? Level design is extremely good? What things contribute to the player feeling comfortable with the difficulty?