The criticism that I've seen recently was due to their choice of Go to implement a router to pass requests to the right back end application. According to their blog post this replaced a previous router written in Scala which nobody really understood. I think they received some criticism for being too quick to pick up fashionable new technologies which then had to be replaced because they were unmaintanable (the scala router).

The poster you're replying to is being very vague though, and I think the downvotes are probably deserved in that case. Either give concrete examples of why you dislike the way someone's doing something, or don't post.