Say ten people come in with similar symptoms but no certainty of Ebola. You quarantine them all as 'maybe'. It later turns out one actually has Ebola. The other 'maybe' cases are now likely at a very similar level of risk to that which they would have been at had they been quarantined with definite cases.

Yes, quarantining them separately is better, but probably not much better, and in many cases probably not sufficently better to consume considerably limited resources.

Summary: I don't think this warrants 'DUH!'.