So that solves the problem of them reading your files, but it doesn't solve the metadata collection portion.
They will still have your location, details of your device, geo location data, probably IP space, not to mention the ability to do pattern of life analysis on you as you modify and move files.
Protecting the contents of your files seems like a logical first step, but that's not the only step.
Why? Just store your files locally in the encrypted vault, which will be synced with Dropbox. And you could even use MountainDuck for the communication between Dropbox and your computer, so you don’t need the Dropbox software (and all the tracking/analytics) at all.
Mainly just that, there's no way to access files except thought the vault software. Other apps, third or first party, can't use them. I can't see them online or use any web documents/shared documents. It basically turns cloud storage into a syncing app, but I can just use syncthing for that.