Yea I got jobs because people at the other companies said "hey that guy knows a lot about this area you should interview him", and when I interviewed everybody

Yea I got jobs because people at the other companies said "hey that guy knows a lot about this area you should interview him", and when I interviewed everybody I talked to gave their approval to hire me based upon a technical interview, so in my area it was not possible to get a job based upon simply telling somebody you are good, you actually have to do well in the technical interview. I was a principal level hardware engineer, so not too low level. Maybe some people are getting jobs based upon just a simple recommendation, but I thought based upon the OP's data science area its more applicable to discuss the typical situation where the recommendation is followed by a technical interview. I don't know of a situation where anybody I worked with who got interviewed because their friend recommended them that the friend left then the other guy lost his job after that. But maybe that could happen if that person was really not interviewed well and the hiring manager was kinda clueless as to how bad the guy was..