What in your opinion is the minimum to be called a "Buddhist"?
Say there's a person who respects Gautama and accepts the Four Noble Truths, but their understanding of the eightfold path and way in which they practice is so different from others. They might not see "Buddhism" as anything special, might not hold to any sect in particular, might incorporate and esoteric practices from other or multiple Buddhist schools (for their own personal benefit while not misrepresenting their own way of doing things as the standard or necessarily the "right way" for everybody) and might not be too consistent but has a practice that is lackadaisical and whimsical. And their morality slips up in ways that would shock people calling themselves Buddhists: whereas most Buddhists concern themselves with crises of world significance like how to stop masturbating or get rid of insects without feeling guilty, this one uses drugs and alcohol, hangs out with street thugs, and he even looks and acts like a street thug -- not carelessly, but to fit in and to learn and because there's nothing else he sees that could be done.
Because of notself, there are no such things as Buddhists. But in the case above, would it be accurate to tell others he is a Buddhist?
If not, then why they ask, what should he say? "I'm a heretic"? "I'm a shaman"? Maybe "I'm an idiot"? Perhaps they could say, "I am a bodhisattva, but I am not a Buddhist"?
The case above seems strange, but I would bet that a lot of western Buddhists are ecclectic in various ways. Here on this forum we have members of the New Kadampa Tradition of Buddhism, right? In your case, by some you are regarded as heretics. Perhaps you might have a unique perspective, then.
Because you can just simply call yourself Buddhist, but you should be clear: because if somebody accepts your view and considers it Buddhist, then when they come across people with a different view who use the same word, that would be a cause of contention.