The problem is, this is one example of field plate that's not late plate armor, which was much heavier and restrictive. It's that later armor, and late jousting armor, that's a problem.
Yes. IIRC, armor toward it's end was significantly thicker in a vain attempt to ward of advanced quality steel, which hit high(er) production rates in the late Medieval, and along with it, the introduction of gunpowder projectiles. The knee-jerk reaction was to make the armor thicker, to the point inevitably, that it ceased to be functional.
Even as keeps faded, as what had worked for centuries didn't stand a bare chance against cannons, which were light and maneuverable, compared to trebuchets - it was not necessarily the power thereof (a trebuchet is arguably capable of more power), but the portability, mobility, and repeatable accuracy of the cannon, is hard for a trebuchet to compete with.
