But the same kind of self-congratulatory exclusionary clique thinking behind frat pledging, and the same thinking behind the historical attendant hazing, could still be at play?

Not necessarily because company leadership and random interviewers are mindlessly mimicking what they experienced in school, but because some ideas tend to arise from power/privilege baggery.

(Though we also now have the mimicking of other tech companies, and we could just call it that, but "frat hazing" is still a better understood term, already with negative connotations.)