gotham 102

For one, manga uses decidedly different techniques for capturing motion and expressions in panels, which most noticeably affects the pacing of each chapter. This is how you can have a chapter of a weekly manga and an issue of a comic, both roughly 20 pages, and so much more happens in a comic or even a complete story could be told in a comic, where manga feels like baby steps by comparison. It can also be why it usually takes much longer to read a comic than a manga. There's more that could be said on this topic, but you get the idea.

As for how it's bad, it could be regurgitating the same tropes or themes that have been done to death but in an all new flavor of awful. just an idea.
i think this may be what he's talking about

I haven't read the comic he's referring to so I don't know if I'm talking about the same thing he is, or if I'm even answering the same question you're asking.