>>63948335
lamellar basically works like modern reactive armor tiles on tanks, absorbing the impact and bending/breaking off instead of getting penetrated like a full plate.

>inb4 heavy thick breastplate that doesnt bulge from impact

Those heavy breastplates were expensive and heavy and you likely didnt have your entire body covered in those. So they protect your torso but everything else is less armored. Also considering your army size, I'd rather have 10,000 men armored head to toe in arrow resistant lamellar than 80 men in heavy plate armor and the rest are men at arms in cheap brigandine like those in the video.