Why can't I hide quests from the tracker?

[SavageWolf]

I think the problem with that though is the FATE sync button and all info no longer appears. If I am not mistaken. I tried it, there was a reason it's turned back on

You are correct. If you hide the Duty List, you also hide the FATE info (and the ability to level sync). So you definitely need it on if you plan on doing any of that.