Perl, Tcl, Python (all scripting, I know) are (iiuc) examples that came to be without a juggernaut behind them, but then to say they had a different kind of marketing behind them is sort of tautological, no? People liked those languages and talked about it. That’s just human nature.
That's a different sort of marketing, though, from the buzz created by having famous/respected names attached to the languges, like Go had in Google and Rob Pike.
- Tcl, was backed by Active State and Sun for a long time
- Python, all the renowned companies Guido worked for
There was never any money behind Python, or C++. Both paid their own way, all the way: people actually using one put in sweat because they believed it made things better for them.
That is the diametrical opposite of marketing.
The contrast is against Sun spending literally $billions on Java puffery. Go has put a lot more support into Go, by that standard, but still barely $millions, if that.
And most programmers probably wouldn't even know about it having any of those features if it didn't have a famous backer like Google and a famous name like Rob Pike attached to it.
Marketing definitely makes a difference. Whether it made a critical difference in this case is certainly debatable, however, as some languages (like Python) succeeded even before they had buy-in and support from big names. Though, there again, Python had a lot of help from marketing.. it was just that it was marketing of a different kind, from its users rather from any company backing it.