I saw the mention of mastery all classes or not in this one from discord. I believe we should be able to master all and choose traits to have active. It allows to focus on one char if we like and could also appease the fans of “Souls style attribute” where you can max out all attributes.
It gives more freedom of testing as well, especially if we level up by using the gear. Seeing I wanna go archer and dislike crossbows. I may start getting a greatbow somewhere and later find a crossbow, I would not want to test it if it could mess up the progress.