The way I see it, a lot of these sites just embed other sites' content (let's call those "JAV streaming sources", JSS). There are only a few of JSS sites, and those might have their own mirrors (that's why there are many MissAV "clones", and I guess it's mostly for accesibility reasons... though I'm not sure why the functionality of MissAV and njav is quite different...)
So, a few JSS sites (possibly with their mirrors owned by them), then a bunch of streaming sites that don't host their own content
And yeah, I see two problems with how these versions are organized on MissAV:
* It clutters the site (it's understandable that de-censored versions get their separate page, but for subtitles, you could just embed those as SRT to switch on and off in the player... I guess they just got the video with the subs already "baked in" or something; basically, they got lazy); but what if I want to see an uncensored version with subtitles (as I understand, there are 3 types of content now: censored without subs, de-censored without subs, censored with subs)?
* The translation is likely a neural network/AI work at most, and even now, for Japanese, it has huge problems (even I, with my low level of Japanese, can spot these mistakes easily)