[rainsford]

I think the best argument for DoH being the killing blow to DNSSEC is that not only does DoH overlap a lot with the security features DNSSEC is trying to be the solution for, but DoH also gives you arguably more important security features that DNSSEC does not and cannot reasonably provide.

This is particularly true if your security model also includes things like TLS to secure your communications with whatever domain you just resolved. In that scenario, the features DoH provides that DNSSEC does not (e.g. lookup confidentiality) are still quite useful, while the 5% of DNSSEC use-cases that DoH doesn't cover are essentially redundant if not better provided elsewhere in your protocol stack.