To me at least, the suttas are a kind of measuring stick. When we hear various teachings, we check them against the suttas to see if they are consistent. If they are, then that teacher is safe to learn from, but if they contradict the suttas, it should raise a red flag and tell us that we should exercise some caution with that particular teacher.
I don't think it is a healthy attitude however to insist that everything a teacher says has to be derivable directly from the suttas as of course, the suttas don't have a lot of detail. Consistency should be our standard, not derivability.
The non-doing of any evil,
The performance of what's skillful,
The cleansing of one's own mind:
This is the Buddhas' teaching.