That rambles on way too long, but it does make a salient point: Space Marines are weird and bad, and attempts to make them just big manly fighty dudes that grunt and fight instead of weird mutant battle-nerds suck and are bad. They shouldn't be relatable, they should barely be human, and they definitely shouldn't be "wot if ur normal soldier man was big and extra fighty?"
Not least of which because Orks already fill the niche of being big silly guys that like to fight.
I think it needed better editing or organization. I just started skimming after the first page worth of text and there were some good points here and there, but it just meandered way too much. It needed to be pared down and condensed into the key points, cutting all the redundant bits and rambling.