Why do some languages have a "Words" tab and others don't?
French has a "words" tab but the Dutch course doesn't. Is there any reason for this?
Duolingo has two course infrastructure systems — one for courses developed in-house (English to/from Spanish, French, Portuguese, German, Italian), and the other for courses developed by volunteers in the Incubator (e.g. Dutch from English). The former system has several features (such as a Words tab) that the latter system doesn’t have.
Some incubator teams are slackers. Seriously I think it was just allocation of resources to the languages with the most users