The author never said they failed because of language choice.
> By 2015, all the Java shops (and many of the C++ shops too) had failed. Lots of companies tried to do something other than C++, but most of them chose wrong.
It's hard to imagine that language choice wasn't a factor - or at least that the philosophical ideals that led to the language choice weren't a factor.
> By 2015, all the Java shops (and many of the C++ shops too) had failed. Lots of companies tried to do something other than C++, but most of them chose wrong.