But the artist has probably fought in a phalanx himself, and many of his customers will have done so as well. Would they not look at an incorrectly rendered hoplite and think "what a load of ^&*%%!" before going somewhere else to buy their vase? I think that they would, because the image would feel wrong to them.

I do like this guy's videos btw. I just don't agree with him on this point.
On the linothorax (not being linen), I think he may be half right, but I would need to look at the sources and archeology myself in much more detail than I care to for this one point.