If anything, this shows that the monolithic telecoms that have large stakes in these cable TV brands are facilitating monopolies elsewhere because likely competitors are locked into their current markets.

EDIT: to be clear, HBO's unsuccessful attempt to be level with Netflix in the streaming arena is more "don't want to" and not "can't". I wouldn't call a lack of wanting to be monopolistic. If HBO suddenly turned around and wanted to compete directly with Netflix and got boxed out by Netflix in some way, i.e. Netflix striking deals with Level 3 or similar providers to prevent HBO from getting equal treatment, then there's a strong case for them being labeled a monopoly.

I'm not sure this is true. HBO Go is available for subscription in the US, is available on many streaming platforms. Additionally, you can subscribe to HBO through Amazon Prime (among other places; I just happen to use the Prime subscription). I can't comment on differences in marketing spend or consumer goodwill, but from my perspective, I see the same level of service between HBO and Netflix (though admittedly, Netflix is usually more stable).

HBO's library is far smaller than Netflix's (though average quality of titles is higher). Their streaming service is also objectively terrible: slow, unreliable, bad UX. On top of that it's 50% more expensive than Netflix. I'm not sure it's just the lucrative TV deals keeping them from competing with Netflix in streaming.

What are you basing this on? They partnered with the same company that Disney just bought to create HBO Now, their video on demand offering. It has 2 million subscribers and is another revenue source for them.

The "problem" with HBO Now is that subscribership spikes when the Game of Thrones starts and plummets when the season ends. Now that the series is winding down, they need to find another one but with their history of great shows I wouldn't bet against them.