x264 was and is a very good encoder for H.264, but it sounds a bit extreme to say that no one can ever beat it - real time streaming was never its primary use case. I think the real lack of motivation to improve it is because most of the interest is now in newer video formats, like VP9. Also, many of the developers of x264 were paid by the commercial licensing program, so I wouldn't say it didn't have any financial motivation.

Also, I'm proof that x264, in fact, does not have a monopoly on Touhou-playing video codec developers :)

Yeah, my comment now looks a bit weird after yaur silently edit the original post to add everything after the first sentence.

I still think “terrible” is a bad choice of wording – “slow” would be an objective statement of fact and the fact that it's within a factor of 2-3 of x264 is worth knowing but hardly enough to say nobody could use it.