MEL
I have heard an old timer reporting to the dispatch :
"There are 42 open items in the Hold Items List (old termninology). I cannot cope with so many defects. I do not accept that aircraft."
And the aircraft was towed back to the hangar ...
There is a provision in the MEL's : final responsibility to accept flying with the defects lies in the captain judgement.
This means that the captain has to carefully analyse each reported defect, and the possible cumulative effects of multiple defects.
Yes, the captain is supposed to know the aircraft systems in depth ... and to have good judgement.