>that is only good for the period of the TTL of the record.
Not really, TTLs are often short, but IPs might not change for years.
You can probably generate your own TTL, at scale, and avoid many DNS requests.
In DNS, the owner of each record has full control over its TTL. Intermediary DNS servers are required to honor them and are not permitted to replace TTLs with their own.
then they would be breaking DNS at scale.
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?