I realized that I was running a very old version of Dropbox for Mac. Somehow I was not notified about the latest updates. I was expecting the same behavior as apps like 1Password.
In the past, I missed out Selective Sync by few months which I was eagerly waiting for.
I was running 1.1.35 (Under Preferences/ Account) and the latest version is 1.1.43 .
Where can I find the config to let Dropbox auto-update/prompt me on every release, similar to 1Password.