Not really a counterexample as zulip started life *outside* dropbox.

I wouldn't really call Zulip a counter-example. It wasn't aband^H^H^H^H^H released to the community, it was spun off as a separate company. They offer paid products, have employees, an office in San Francisco, etc.

OT, but: ^W deletes a word, so you don't need to spam ^H. (Though it is a dangerous habit when writing in a browser tab.)