I thought it was weird to credit someone as Diablo's "creator" since there must've been a large team given how long I remember the credits being. But indeed if you look at the wiki he seems to be the main programmer listed: https://en.wikipedia.org/wiki/Diablo_(video_game)
Some other team members such as Max Schaefer and Erich Schaefer (co-designers of Diablo and Diablo II) went on to make Torchlight so many consider it to be Diablo's spiritual successor: https://en.wikipedia.org/wiki/Torchlight
Some other team members such as Max Schaefer and Erich Schaefer (co-designers of Diablo and Diablo II) went on to make Torchlight so many consider it to be Diablo's spiritual successor: https://en.wikipedia.org/wiki/Torchlight