Unfortunately the user experience for a DNSSEC signature failure is so bad, the only option if you run a large ISP or corporate network is to just use the answer you get anyway.
In fact, I see a lot of people advocating for using centralized resolvers, and not even once have I seen a counter-argument in the form of DNSSEC validation being a problem.
Many recursive servers do validate DNSSEC, but disable it on a per-zone basis when validation failures happen and users start to complain.
tptacek raises an additional good point that DNSSEC does nothing to protect the last mile of a query. It also provides zero confidentiality.
dnscrypt was always a superior implementation, but saw little uptake because people blindly believed the DNSSEC propaganda.
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?
It's very easy to just check this for yourself. There are increasing numbers of domains signed every year, because registrars and product companies have baked DNSSEC in as a feature. But the vast majority of zones don't matter: nobody ever looks anything up in them. The figure of merit is how many important zones are signed.
Amusingly for this method to work the resolver must understand DNSSEC. This is because DS records exist solely at the parent side of a delegation. A resolver that is not aware of DNSSEC will look to the child as it would for any other kind of record type.