Agree with completely. Rosewood and ebony, which is what most
fingerboards are made of, do no need any 'moisterizing'. If you have a
fingerboard cracking or splitting because it's too dry, then it must be
from the last millenia (time to call a museam). Also Keep in mind any
oil you add to the fingerboard will also transfer to the the strings,
and oil on the strings (especially the bass E, A, D) is not a good
combination.

No oil, just TLC.