The "have you written" argument is with respect to the writing process. Critiquing a book's content without writing one is fine, critiquing the process or describing an author as lazy is something altogether different.
It is important to contextualise what a colossal undertaking a book like this is. Even if GRRM wrote 1000 perfect words every single day, without the need of editing, one of his books would take over a year. LOTR, which clocks in a little longer than Dance with Dragons, took 12 years to write and a further 6 years from that to get published (during which time parts were revised and rewritten). Gone with the wind is around the same length as Dance with Dragons and it took over a decade.
https://fivethirtyeight.com/features/predicting-when-game-of-thrones-author-george-r-r-martin-will-come-out-with-his-next-book/Fivethirtyeight did a jokey article about this all the way back in 2014. It's jokey, but it still has some half decent analysis in it, if only because it includes the rate at which he's done previous books.
He's never written more than 700 (final) words a day while writing this series. At his fastest, when he had a cohesive plan, he pumped out A Storm of Swords at a rate of around 673 words a day (incidentally also undoubtedly the best book of the series).
For 'Feast' and 'Dance' his speed was more around 150-200 words a day.
'Dance' was 415,000 words. If "Winds" is the same length, and he wrote at the slowest speed he's written one of these so far (145 words/day, for 'GoT'), he would have finished about 6 days ago (calculating 145 words a day from, for the sake of argument, the release date of 'Dance': 12 July 2019).
If he's down to about 2/3 of his slowest ever speed, to about 100 words a day (which I think most writers would agree, is slow), to produce a work the same length as 'Dance', 'Winds' will take 11 years and we'll get something in around 2022.
I don't think GRRM is lazy, but I think we should dispense with the idea that he's being held to the speed expectations of some sort of fantasy-writing robot. He's not been a fast writer in the past. Currently he's a slow writer. But there's no point in feeling upset or unhappy or defensive about it, because it's entirely out of our control. The guy is who he is, and he'll work at the speed at which he works. He's accountable ultimately only to himself and we'll get the book (or not) when it's finished.
And here's another article which hilariously projected an early 2017 finish date:
https://fivethirtyeight.com/features/heres-the-best-new-projection-for-when-the-next-game-of-thrones-book-will-be-done/
