I mean, heresy was invented to suppress politically conflicting directions of Christianity. Gnosticism was a popular direction at one point in history, dominating the "mainstream" in some parts of the world. There were more Marcian churches than trinitarian. Gnosticism is only weird from your perspective, after it was already basically outlawed. Admittedly, that is probably a valid justification for calling it with weird, but I'd like to make a distinction that it is not weird on its own, only because it got banned. In fact, in the context of being influenced by Greek philosophy, it was quite logical. Judas gospel was probably not written by Judas, but other, canonical gospels werw probably not written by original authors either, at least some of them.