The primary purpose of my project folder is to contain my project, including source, dependencies, build output, etc - so it makes sense to me that tools like Git allow you to exclude/ignore parts of it.

But the primary purpose of the Dropbox folder is to sync stuff to Dropbox. The idea that I would put something in my Dropbox folder that I didn't want to sync is bizarre.

It sounds like it's a common case where people put their project folders inside their Dropbox folder. Before today it never occurred to me that anybody would do that.

I do have some projects I periodically Git Bundle into a Dropbox folder though.

Not criticizing anybody's workflow, just surprised it's so common.