It isn't true. People get that from Anchell.
See Bob Shanebrook's book which includes photomicrographs of cross sections of both TMY and Tri-X 400 (TXP 320 isn't part tabular either). In fact it's the tabular film which is part tabular since it also has non-tabular grains.
So don't worry if you don't like tabular grains [not that I agree with the assertion tabular films "look" different (aside from being finer grained of course) but anyway...]. Tri-X, TXP, FP4, HP5 are still traditional grained emulsions.
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