We could also be relying on DNSSEC+DANE, where the domain owner publishes TLS public keys via DNS. Without a third party CA.
The main limitation right now is browser support. Browsers _only_ support CAs, so CAs continue being the norm.
The main limitation right now is browser support. Browsers _only_ support CAs, so CAs continue being the norm.
Another problem with DNSSEC is that the root is controlled by the United States. If we start relying on DNSSEC, America gains the power to knock out entire TLDs by breaking the signature configuration. Recent credible threats of invading friendly countries should make even America's allies fearful for extending digital infrastructure in a way that gives them any more power.
We've spent a decade and a half slowly making the Web PKI more agile and more transparent by reducing key lifetimes, expanding automation support, and integrating certificate transparency.
None of that exists for DNS, largely by design.
The only real downsides are that DNSSEC doesn't have CT yet (that'd be nice), this adds latency, and larger DNS messages can be annoying.
[0] QName minimization means if if you're asking for foo.bar.baz.example. you'll ask . for example. then you'll ask example. for baz.example. and so on, detecting all the zone cuts yourself. As opposed to sending the full foo.bar.baz.example. query to . then example. and so on. If you minimize the query then . doesn't get to know anything other than the TLD you're interested in, which is not much of a clue as to whether an evil . should MITM you. Now because most domainnames of interest have only one or two intermediate zones (a TLD or a ccTLD and one below that), and because those intermediates are also run by parties similar to the one that runs the root, you might still fear MITMing.
But you can still use a combination of WebPKI and DANE, in which case the evil DNSSEC CAs would have to collaborate with some evil WebPKI CA.
Ultimately though DNSSEC could use having CT.