This is simultaneously good and bad advise.

Good, because it is correct in the absolute sense.

Bad, because it lacks humility.

What if observation and experiment fail us?

What if our own conclusions are wrong?

Authorities are authorities only because we trust them. That trust is a powerful tool to gain access to a body of wisdom beyond what we can discern for ourselves. Use Feynmen's advice not to reject authority, for then we merely substitute ourselves, but rather to discern who to trust.