Both privacy and security are layered, and perfect is the enemy of good. Securing the DNS is an obvious first step, forcing the Internet to HTTPS by default was another. Google and Mozilla have contributed to better privacy. People that want more privacy, depending on needs, can also use a VPN or for the more extreme cases, something like Tor.

Not sure what you mean about having to trust Google or Mozilla. I'm not using either Google's or Mozilla's DoH servers. But yes, I would trust them more than my local ISP. Google, at least, proved quite competent in handling whatever data they collect.