A litra of Syracuse may have bought dinner for Archimedes. Every ancient coin is a story. And if you love historical research, ancients are an always-unexplored world. Very few coins, no matter from what seller, come fully attributed. You can always add a BMC or SGC number, find a coin in an SNG or special volume.
Minor oversights abound.
World-leading sellers let go of unusual bargains, not knowing what they owned. Nine million Owls is not a lot by modern standards. Most coins were struck in much smaller numbers. Die-matching is an important part of ancient numismatics, as the reverse dies tended to break much sooner than the obverse, perhaps 5 to 35 thousand to an obverse and 2 to 15 thousand for a reverse. In short, if you rely on other people's opinions, ancient coins are a flat out rip-off.