See comment from gedy elsewhere in the thread. Multiple people have pointed out these kinds of questions being asked well past 2006.
Since there is no incentive for a large number of engineers to cook up stories about their interview experience at Google, I am calling this smoke as having some fire behind it.
But what's the incentive for a large number of Google engineers to surreptitiously ask questions of a style that's explicitly banned?
I think there is incentive for failed interviewees to cook up stories - or at least to tell something very one-sided - because none of us like to believe we failed at something and feel better if we persuade ourselves it was stacked against us.
The most persistent critique I have heard about Google is that the experience can be very uneven in everything from recruitment and workload to even salary for the same job. Even if Google entirely stopped with brain teasers, people certainly seemed to have expected them on account of unpredictability up until a few years ago.
The incentive is just not having to come up with and calibrate new questions. It takes a lot of effort to do that, and if you've been asking a "banned" question for a while and are comfortable with it, it's easy to just keep using it until someone explicitly tells you not to (reverse feedback from hiring committee to interviewer wasn't a thing for a while). Most engineers don't really enjoy interviewing and want to put minimal effort into it.
And in fact there's no need for explicit animosity by the failed interviewee. Someone who misunderstands a question badly enough to call it a brainteaser when it isn't is also likely to have performed badly on it.
I've certainly met people who believed that anything other than (for example) an android ui question with open book stack exchange was a dumb brainteaser with no relevance to the actual job...
For my part, about every few months I hit something that would make a great interview question, and then have a wonderful afternoon coding it up... Ymmv.
I have a much higher faith in the capacity of the Internet to produce liars, trolls and delusionals than you apparently have.
This is an open internet forum for anyone to type anything they feel like in. Of course, as far as you know, I might be an Uzbeki 12-year old, so that argument only goes so far...
I can imagine that Google interviews for other roles than Software Engineers can have any kind of wacky questions. But mostly these stories sound so much like the stories that used to go around about Microsoft interviewing, only with the company name switched, that I have to think it has to do with their inherent virality somehow.
Since there is no incentive for a large number of engineers to cook up stories about their interview experience at Google, I am calling this smoke as having some fire behind it.