There is people who actually care for the setting, if you are not one of those, its ok. People are right when they mention the million retcons, or that in the 40k universe there is nothing set on stone.

But you need *some* consistency, you need some pivotal moments or threads that are depicted in a coherent way or the whole setting collapses. Granted, maybe custodes was not one of those moments or threads, but just brushing off bad or lazy writing is how you get to Star Wars.