I agree that this is the kind way to look at it. Some people aren't cut out to be caregivers. Still, some in the community have done all the work yet are criticized by the siblings. They'd maybe feel more love for the sibling if he or she didn't criticize the caregiver's efforts.
You may enjoy this article: https://www.agingcare.com/articles/not-everyone-cut-out-to-be-a-caregiver-162192.htm
Take care,
Carol