Families like the malfoys were more than willing to serve lord voldemort, whose father was a muggle (not even. Here's the quote from chapter 35, harry speaking to death eaters in the dept. It validates the pure blood doctrine;
We also know from the movie that voldemort was living with muggles before hogworts in a orphanage. Lucius might know since he knew about the chamber of secrets and the diary. Very few people know he is tom riddle.
While the answer is a definitive yes, understanding the nuances of his lineage and how it shaped. Through his pensieve, dumbledore shows harry what shaped tom riddle,. Other than him, i don’t see how anyone else could. If even a half blood supports it it “must be true”, isn’t racist etc.
Several time in the book harry throws that in people face that voldemort is a half. It is possible that his followers do not realize this, since bellatrix acted as though. The canon evidence is not conclusive. He also benefits from exceptionalism.
Voldemort’s half blood status works on a few levels. Why didn't voldemort choose to eliminate muggles first which would have.