In my opinion, they failed to adapt to the market, considering the number of streaming platforms that have appeared in the last few years and have become serious competition. I personally have several streaming services and I don't want to advertise any of them, but I will say that the one that currently has the LOTR series in its offer really has a much better offer of movies and series than Netflix.
As @TelolettOm nicely quoted, it's not that Netflix has something against Bitcoin, but they simply don't want to advertise such things through their platform, along with gambling and politics. A lot of scammers would take advantage of this, and users would then point the finger at Netflix because they lost money because of the advertisement that service showed them.
As for Bitcoin documentaries, I only watched one about QuadrigaCX (Trust No One) a few months ago, but I'm not sure it's still available - because Netflix often removes content after a while, although it might be related to different regions - so what is available in the US is not in the EU or vice versa.
They've also put prices up, and I know there was a lot of issues with account sharing which they said they'd crack down on. I was already away from Netflix at that point though. I got sick, and tired of watching a show, and then them removing it.
Yeah, I did understand that they don't want to advertise it, along with a few other things. However, I'd love to be a fly on the wall to actually know the reasons. I understand with politics, since that can cause controversies, but is Bitcoin that controversial? Scamming is an issue I suppose, but they'll advertise fiat based companies, which could potentially scam you. I mean big companies seem to get away with it all the time. I've seen how the big companies pretty much scam the smaller companies out of money, and it usually goes unpunished. This is especially true with limited companies in the UK.
I never watched whatever documentary was on Netflix since I didn't have it, but I'm pretty sure they had one on Netflix. I'm only interested since they've also banned political advertisements, I wouldn't expect they remove political movies/documentaries, but if they've removed that documentary about Bitcoin is that simply because it was part of their routine removal schedule or because they don't want anything Bitcoin on their platform. I'm just curious, I'm not trying to put the tin foil hat on.