As opposed by your "trusted" partner ie. your internet provider? Ignoring that these are the organisations that keep getting hacked, they also outright try to monetize your DNS queries whichever way they can (even falsifying real sites).

And that's ignoring the obnoxious government interference ISPs tend to implement through DNS. From piratebay to youtube blocks.

You have to trust someone with DNS. And Firefox's trusted partner is better than the current status quo.