The idea that Ember is made by/for small and medium sized companies is a bit dated. Several Ember and Ember-CLI core contributors have and continue to work at larger companies like LinkedIn and Yahoo.
In particular, LinkedIn has been using Ember (with Ember-CLI) for over a year now and has found a lot of benefits from its adoption. Having a build system and conventions that a community maintains lets us focus on building applications instead of tooling (though we still have our share of internal tools). We also can give back to the community for things which matter more for applications "at scale". LI, for instance, funded a good portion of the FastBoot work and has been a key driver in the Ember Engines effort recently.
All that to say, Ember (and Ember-CLI) can serve the needs of the whole spectrum of company/team sizes. While it still has some issues to sort out for larger applications, to say it isn't being influenced by large companies isn't really accurate any more