I personally love playing precon decks bone stock. To me trying to make someone's deck work adds to the challenge of the game.
The last precon i upgraded was one of the 2018 decks (other than a league i ran where part of it was upgrading the deck, but it was returned to stock after the league).
I also own many, many precon decks, so i have a large choice so they do not get stale.
The Finally Fantasy decks were fun, i have only played Yshtola, and Cloud, possibly Titus.
As was mentioned by mirodir, commander as a new player does not teach you how to play magic. It teaches you how to play your deck.
I owned an FLGS for over 7 years, i saw countless new players learn playing commander and never understanding how the rest of the game works.