A few days ago, the pony YouTuber Cxcd released his final G5 video essay, "How G5 was ALMOST the Greatest Generation". To my knowledge, this happens to be the first fully-fledged review of why Hasbro's strategy imploded, so it's worth a watch if you're curious.
Cxcd's video is over 30 minutes long and is comprehensive and detailed; this article's purpose is to outline some of the important information and arguments presented in the video.