It's a conspiracy, but not from the industry, which has broadly rejected it. :)
What “industry” would that be? Certainly not the DNS industry, or their customers (i.e. anybody who wants a domain name). Do you mean “rejected” in the same sense as how IPv6 is still only slowly being adopted?
If validation failures were that common, I would think I, working at a domain registrar and authoritative DNS provider, would hear about it. The last mile problem would be solved by DoT/DoH, no?
If anything is a “dead horse”, it’s dnscrypt. Are you claiming that DNSSEC is some sort of industry conspiracy?