Well that would be shocking if it were true. There is without a doubt a spectrum of thought among Buddhists on the subject. Even the Dalai Lama’s website has a section discussing reincarnation.
From my observation it is mostly western Buddhists with a materialist bent that eschew all things paranormal/supernatural like rebirth.
No. A lot of Us believe in rebirth (supernatural, if you like), etc just other countries overlook that we actually have a spiritual side like other countries do. We are multicultural so a lot of "American Buddhist" or Dharmic Practitioners (no America back then) are singled out in monasteries and laymen depending on the area and who they know may help the monks as The Buddha advised of us laymen.
I never got where the "western culture" as negative came from. An American is just someone of US Citizenship. Those born and raised as Americans are a dime a dozen and those white and black whose historical built Americans are mixed between christian, African religions, muslim, and couple others.
If you asked us individually about our beliefs many aren't westernized. But generalizing as a whole all we eat is cheese burgers materialist, atheist, politician, none spiritual people is highly intuitive to us individually.
It's a pet peeve. I was told in China (and someone from there) told me there isn't really a religion there. I don't know about the rest of Western culture from in part eureopean and other western sides of the world but America is pretty supernatural based. Political and media is bad influence on who we are.
