This would be true if peak performance was mandatory for clearing all content. The vast majority of the content is incredibly lenient and people already play suboptimally most of the time (just take a quick look at any random page in Tales from the Duty Finder), so I don't see the harm in having options for flavor. Even in "hardcore" content you're gonna find a big enough gap in skill between the absolute top players and the people who can barely clear the content. Many times there's even room to carry people, maybe not on day 1 but eventually with good enough gear. If you're struggling sure, you may want to have any advantage at your disposal including the most optimal build available to you, but anyone above that point should have enough room to sacrifice some efficiency if that allows them to engage in a playstyle they'd enjoy more while still getting the job done.