I think it used to be that one needs to write dedicated programs to go through large amount of data --- you need to know a programming language, all its toolcha

I think it used to be that one needs to write dedicated programs to go through large amount of data --- you need to know a programming language, all its toolchains, and the all the proper algorithms for doing the query __out-of-memory__ --- certainly above your ordinary analysts' paygrade. With SQL you need none of those.