If "marketing" means anything, it means money buying influence, independent of actual users. It might be spent on press, "analyst" puffery, huge library developments, book projects, and lavish conferences, as Sun did for Java.

Money spent developing compilers and libraries to sell at a profit is not marketing, even if the compiler is marketed: that money comes from users already committed.

C didn't need marketing. It rode on Unix, which also got hardly any. Unix rode on workstations, which had to be marketed hard against all the minicomputer and, later, mainframe competition.

C++ got no marketing either. It still has none, yet the number of C++ programmers is growing faster than ever before. Complaining about it is always popular, but as Bjarne says, there are only two kinds of language : the ones people complain about, and the ones no one uses.

Go may be counted a success when it is complained about as much as C++ or Python.