[Ron Ramirez]

Because there were radio manufacturers (Philco and Zenith chief among them) who refused to go down the RCA/GE metal tube route. They chose to use Sylvania-built ST glass tubes with octal bases instead.

With the possible exception of a very few Simplex-designed small Philco table model radios (Philco ultimately bought controlling interest in Simplex), I can't recall a single Philco radio which ever used metal octal tubes.