Indeed much scientific computing these days is "high-throughput" rather than "high-performance" computing [1], and is done on commodity hardware, including commercial clouds. However there are certain classes of problems that still need highly-connected leadership systems [2,3], but that distinction is definitely blurring.

[1] https://www.opensciencegrid.org/ [2] http://www.nersc.gov/ [3] https://www.alcf.anl.gov/