Wicca is only a few decades old, created by Gerald Gardner who crafted it with some influences from other older practices. Some even say with slight help from Alistair Crowley.
That is not to say that Wicca is any less valid than any other religion, as they all had to start somewhere.
I think in a strict technical sense you're right. Gerald Gardner used the term "Wicca" to officially label his religion when going through the government bureaucracy to have it officially recognized by the U.S. government as a valid religion.
That bureaucratic process "forced" the religion to become a bit "dogmatic" (i.e. based on a specific doctrine). Mainly the doctrines that Gerald himself wrote up to describe the religion.
However, if you read many books that are written on the topic of "Wicca" they do not adhere strictly to the doctrines of Gerard Gardner, nor do they even use his pantheon in any absolute sense.
Most books and websites that you read about Wicca are far more abstract than this.
Christopher Penczak was fully aware of this and thus entitled his serious of books "Temple of Witchcraft" books, rather than "Temple of Wicca" books. He wasn't about to be confined to a governmental bureaucratic box.
I believe that most pagans who practice witchcraft either refuse to call themselves "Wiccans" altogether, or if they do associate with "Wicca" they do so in an extreme abstract sense.
The modern "Wicca Movement" (based on what can be seen on most websites that claim to be "Wiccan" web sites) tends to be far more abstract and less dogmatic than anything that could be seen to be tied down to precisely following Gerald Gardener's Book of Shadows, etc.
This is a problem with a religion that is so free from doctrine. To be free from doctrine entirely would appear from a bureaucratic governmental point of view to simply be non-existent, or undefinable, and thus could not be "officially recognized" as a valid "religion".
It's a truly tricky situation.
Define it precisely enough to make it recognizable to bureaucrats and it becomes dogma. Leave it as abstract as witchcraft natural was, and there's nothing concrete enough to register as a 'religion' as far as bureaucrats are concerned.
This is why I typically don't even bother with labels.
Am I a "Wiccan"? Well, that all depends on who's definition you go by.
I don't need to claim to be anything. I am that I am. And that's all I need to be.
I think Ruth posted a "Witch's decree" along those lines at one point.
