There is just no good reason to announce release dates with so many months, or sometimes over a year in advance. Gaming studios (at least triple-A studios) no longer need to setup distribution chains in advance, and they no longer need any external "press" coverage or reviews, they have their own communication channels for marketing and outreach, and digital distribution can be setup in a few days at most.
To be fair to CDPR in this instance, 1) there was always going to be a huge amount of interest in anything they do after the creative & commercial success of Witcher 3, and 2) there's a truly vast array of merch available and "limited edition" this or that, which has no doubt gone some significant way to funding the development of the game. Some hype is good, but a lot of it is reflected rather than generated by CDPR themselves.
They would have been better served though by saying "Release Q4 2020" rather than try and nail down specific dates which they then miss. I'm sure they've learned from that.