Imo, someone who is permanently disabled and has no hope of recovery will not live long.
That's not a reasonable assumption.
On recovery, DI payments will stop.
Yes, and income from work will restart, i.e. the loss ends. Note that partial disability is covered -- DII "tops up" income to the insured amount if necessary when the policyholder is partially disabled and cannot earn as before.
Many DI plans have escalating requirements for claims e.g. Unable to do own job for 1st year claims, subsequent years- unable to do any jobs or 3 out of 6 ADL
That's not how these policies work. They apply ability to work criteria (own profession then later any profession), not 3 out of 6 ADL criteria.
There is also a safety net called CareShield Life.
Which does have a 3 out of 7 ADL definition of disability, i.e. it's quite strict. CSL supplements can get to 2 out of 7, still strict. Moreover, CSL, even with supplements, cannot really replace much of an income loss on a percentage basis. DII can replace up to 75%.