That works nicely for maths but any subject that requires a non trivial amount of data gathering needs to be build on a certain amount of trust.
.. there are too many Prof. Dr. Dr. that did not "cheat" but still claim covid isn't real .. so the title really doesn't mean anything at all to me .. also having studied myself seeing what kind of idiots also got their exams .. it's maybe just a proof they can 'write' and 'read', but even believing this would proof 'understanding' is a big overestimation of the title itself ..
Peer review does not even attempt to control for fabricated experimental results or other data.