Timaeus and his admirers are in the same case as regards history. For being given to paradox and contentiously defending every statement, he overawes most people by his language, compelling them to belief by the superficial appearance of veracity, while in other cases he invites discussion and seems likely to carry conviction by the proofs he produces.
He is most successful in creating the impression when he makes statements about colonies, the foundation of towns and family history.
For here he makes such a fine show owing to his accuracy of statement and the bitter tone in which he confutes others that one would think all writers except himself had dozed over events made mere random shots at what was befalling the world, while he alone had tested the accuracy of everything and submitted to careful scrutiny the various stories in which there is much that is genuine and much that is false .
But, as a fact, when those who have made themselves by long study familiar with the earlier part of the work, in which he treats of the subjects I mentioned, have come to rely fully on his excessive professions of accuracy, and when afters someone proves to them that Timaeus is himself guilty of the very faults he bitterly reproaches in others, committing errors such as I have just above exhibited in the cases of the Locrians and others;
then, I say, they become the most captious of critics, disposed to contest every statement, difficult to shake; and it is chiefly those who have devoted most labour to the study of his works who profit thus by their reading.
Those on the other hand who model themselves on his speeches and in general on his more verbose passages become for the reasons I give above childish, scholastic, and quite unveracious.
Walbank Commentary