We both know that DSA isn't demcent; it needs more centralization to really develop its demcoracy, but it needs to avoid the errors of bureaucratic centralism too. A big part of the problem with DSA is big chapters like NYC and LA don't want to be democratic; they want to bureaucratically decide things and get rubber stamps from membership.
There's also advantages to handling some disagreements publicly: it renders line struggle visible to the masses.
Finally, as I alluded to above, some MLs like Mao have definitely been okay not just handling stuff internally.