Delia Derbyshire's groundbreaking work at the BBC Radiophonic Workshop deserves special mention here - her realization of the Doctor Who theme and pieces like "Blue Veils and Golden Sands" represent a crucial bridge between academic electroacoustic experimentation and more accessible electronic music.

Is it? Why do you feel that excluding those particular pieces and people make the list snobbish?

All listed are excellent consumers of the techniques pioneered by the people on OPs list. It's not that the artists/examples you listed are bad, they're just not remotely on the same level as someone like Karlheinz Stockhausen. If you don't understand how the two groups are different you underscore your own point.