Why do people refer to the 11-minute era as part of the original series but to Dragons Rising as a separate series?

This might be a silly question, but as far as I know, the 11-minute era is a separate series, and I think you can tell by the change in animation style, length, and worse writing. But I see that many people don't know it's a separate series and that the original series ended with season 10. I also understand that it must be because the title of this new series is simply "Ninjago," and that makes it hard for people to tell them apart. I also think it wasn't a very good decision not to give it...