What part of "Forget the power of technology and science, for so much has been forgotten, never to be re-learned. Forget the promise of progress and understanding." do you not understand? The fact that the Primaris could even be conceived as an all new, all better technology in the Imperium totally flies in the face of some much the setting stood for. More than that, they incorporate shit like rail systems and foregrips to their guns to make them look more tacticool and modern, when the whole setting is intended to look backwards and gothic.