Why would anyone want to use a DNS resolver that tampered with records on a large scale? The TTL is intentionally set by the originator of the record.

Or alternatively, if you don't tamper why would I want to use a service that serves stale data?

Every distributed system serves stale data.

You can define away ‘stale’ by picking a consistency model, but look inside the consistency machinery and you will see fresher data you aren’t allowed to have yet.