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.