This guy has never seen a 737 upclose. "Boeing reduced the amount of flaps you can use for landing and takeoff when the 737 was stretched" Flaps 40 has been there since day 1 and unlike the
737-300/400/500, which can use 1 (not -400), 5 and 15 for takeoff, NG and MAX can also use 25.
A320, which is a much newer design that the 737, also proves very well that there's no problem having only four main gear wheels on a narrowbody aircraft even with much higher MTOWs than 737-800.