A reason for why Leucippus isn't credited the original "atomist" in the norm?

Question

His exact contributions are difficult to disentangle from those of his mentor Leucippus, as they are often mentioned together in texts. Their speculation on atoms, taken from Leucippus, bears a passing and partial resemblance to the nineteenth-century understanding of atomic structure that has led some to regard Democritus as more of a scientist than other Greek philosophers. Democritus, wikipedia

I don't know if this is only in my home country or is widespread in the world. In here, Democritus is the person that's known to be the "pioneer" of atomic theory. However, Leucippus is well known to be his master and the teachings of Democritus are almost unanimously been linked with that of Leucippus. Then why is Democritus credited with atomic theory invention? Why isn't the student-and-master relationship applicable in here? (If both master and student have brought up an idea into development, shouldn't the master be credited more?)

Fun trivia: The SE spell checker finds Democritus legit, while Leucippus is a spelling mistake! This should mean that Democritus is more credited everywhere.

Answer 1

Wikipedia article on Leucippus pretty much answers your question: "a brief notice in Diogenes Laertius’s life of Epicurus says that on the testimony of Epicurus Leucippus never existed. As the philosophical heir of Democritus, Epicurus's word has some weight... Furthermore, in his Corpus Democriteum, Thrasyllus of Alexandria, an astrologer and writer living under the emperor Tiberius (14–37 CE) compiled a list of writings on atomism that he attributed to Democritus to the exclusion of Leucippus."

Scholars preferred to give credit to the person that they were confident actually existed. Now the consensus has shifted, and Leucippus's contribution is recognized more independently as in "mechanistic determinism, which seems to go back to Leucippus, and the distinction between primary and secondary qualities, which appears in Democritus" from Russo's Forgotten Revolution. Graham even notes some possible differences: "Rather than logical abstractions, Being and Not-being, Leucippus' atoms would in essence be based on Parmenides' cosomological contraries, night and light. If this line of interpretation is followed, Leucippus' notion of atom and void might have been rather different from Democritus".

Over time it will enter more popular accounts, but slowly, many popular texts still repeat myths about Pythagoras despite the contrary consensus among scholars since the Burkert's book of 1972.