Same reason as why Google has buried open standards like RSS or XMPP based GTalk.

Seriously I do not think that the stakeholders' values of Google are the same as the ones by the Mozilla fundation (which also has a corporation but mainly due to taxing and employing reasons).

I'd even say: The moment Firefox would not exist anymore, we there would be not-so-user friendly changes to Chromium or Chrome in the interest of Google. http://robert.ocallahan.org/2014/08/choose-firefox-now-or-la...