I think leetcode style interviews being easy for the interviewer / company is the most rational explanation for why its so pervasive. Its easy for the company as an automated screener and an on-site because there is a clear pass / fail rubric that can filter people. If you have a bunch of people doing interviews that don't want to do it (Google and FB interviewers cough cough), then this style of interview is perfect for the interviewer to conduct if they just want to get it over with.
I've noticed that Apple only uses simple leetcode-y style questions for its phone screens, but for their on-sites they ask very domain specific questions. It is interesting because if you're actually good at the domain you're interviewing for, they are very easy. If you're not they can be intractable. Its clear that each team puts a lot of thought into the interview process and I imagine Apple teams get a very high SNR, at least compared to Google / FB.
I've noticed that Apple only uses simple leetcode-y style questions for its phone screens, but for their on-sites they ask very domain specific questions. It is interesting because if you're actually good at the domain you're interviewing for, they are very easy. If you're not they can be intractable. Its clear that each team puts a lot of thought into the interview process and I imagine Apple teams get a very high SNR, at least compared to Google / FB.