Add .dropboxignore directory to exclude folders without using selective sync

No, this has NOT been delivered. The proposed solution is not what we are asking for. 

First of all, it isn't cross-platform.

Second, you have to specify it on every machine you synchronize to. 

Third, and most importantly, the information on what folders should be ignored disappears if the folder is deleted. Many tools create folders on the fly, eg node_modules, and just recreate them if they have been deleted. 

Fourth, there are concurrency issues. Computer a creates node_modules and starts to synchronize it. You ignore it and it is deleted from the cloud. Computer B now creates node_modules and synchronizes it. What is computer A now supposed to do with the new cloud folder that it ignoes?

Just implement a .gitignore style. It is not that difficult. koofr has it, and it works flawlessly.