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;
Did the Deatheaters Know Voldemort Was a HALFBLOOD? Harry Potter
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.
Voldemort was ashamed of his muggle.
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.

Yeah, his mother was a witch but his dad was a.
Voldemort’s half blood status works on a few levels. Why didn't voldemort choose to eliminate muggles first which would have.

