Sure, google.com probably needs to support IE 6. For my own business, I'm not willing to make compromises for browsers below 2%. That currently means Safari 10, Chrome 56, and IE 11. And IE 11 is really stretching it by now–next time it gets in my way, I'll give people a reason to upgrade.
Now I don't have "enterprise" customers, and it's a rather small business. For anything medium-size up, the calculus changes, and probably makes it worthwhile. But at some point, these mystical "enterprises" really have to get their act together and stop dragging technology back to 2006.