Yes, I used to have the same problem. It used to feel like it was full of invisible and unwritten rules that all contradicted each other. Getting bullied if cards are too strong or too weak.
Casual EDH, that is: as you point out, competitive EDH doesn’t have the same problem.
What I finally realized was that I shouldn’t approach it as a game. I should approach EDH deckbuilding like a crossword maker approaches making a crossword:
To try to create something that is a challenge but beatable.
It’s easy to create an unsolvable crossword. Just a bunch of white noise in a grid. But that’s just no fun to anyone. A good crossbow maker wants the crossword solver to have fun and to enjoy the puzzle, to tease them a bit but keep it realistic and grounded.
Now, a game of EDH isn’t a puzzle, but it’s an experience.
I started out making my first EDH deck super weak (it’s built around Tolarian Serpent) and have gradually been adding powerful cards or interactive cards or cards where I just like the art or the experience or the memory of when I first opened the card. I have a foil Rethink even though there are a lot better stack interaction cards, but it was just the first foil I ever opened so playing it makes me happy. The deck is still weaker than many of precons are out of the box so I still have a ways to go with it but that can be a gradual process of tweaking and modding.
I hope this helps.