This announcement relates to their Japanese domestic product 富士フイルムカラーペーパー（CLP）(Fujifilm color paper).
Yes, that's right. For the rest of the world, the situation varies. In some locales, there's cut-sheet paper being sold in Fuji-branded boxes, supposedly cut & boxed either by or
for Fuji. There's also places where 3rd parties cut & box sheets of Fuji RA4 paper, sometimes under their own brand name, sometimes under Fuji's product name, but no logo etc. And in some places, there's just no Fuji cut-sheet to be had, only rolls, or not even rolls.
So...it varies.
this stuff was optimized for optical enlargement by enthusiasts
If this is about the paper linked to in post #1: well...possibly. It's never quite clear what's happening in Japan. If it's "optimized for optical enlargement", the most likely scenario is that this is just an old formulation from 20+ years ago when color paper was optimized for optical enlargement
by default. Somewhere in that timeframe this 'optimization' was abandoned because that niche sort of disappeared, and the combination of digital dominance and economics (i.e. cost-down) dictated optimizations that resulted in slightly less optimal performance when the paper is used for optical printing. In practice, it's not all that much of an issue because the "digital" papers print quite well, optically.
However, I understand that when European RA4 paper manufacture definitively abandoned the full optical enlargement optimization, there was some pushback from Fuji Japan as they were concerned about this. I don't know what those concerns were, except that they were ultimately brushed aside. My interpretation is that Fuji Japan wanted to maintain that optimization as a courtesy to the remaining few analog printers, but that the European entities saw no way to rationalize a relatively costly legacy in the face of competitive pressure, and that the economic argument prevailed. Mind you, this is years ago.
To the best of my knowledge, no Japanese-made Fuji RA4 paper has been retailed in the US or Europe, or indeed most of the world, outside of Japan (this does not apply to FujiFlex, which is only made in Japan and sold internationally, but it's technically not a paper). So indeed, the disappearance of this particular cut-sheet product, which may or may not have been a relict of the old pre-digital era, is kind of moot for most of the world. It has very little practical implications one way or another: it wasn't available to begin with, and effective alternatives have been available all this time.
Take the US website with a grain of salt. It's not necessarily representative of the actual papers manufactured. E.g. it still lists the FujiTrans product line, which was discontinued several years ago. To complicate matters, papers manufactured in Europe (which is what you buy in the US) are sometimes sold under a different product name in the US, even though it's the same paper. The net result is that the US website can contain reference to papers that are no longer made, papers that are made and sold under a different name in Europe, and papers that are available in Europe by the same name.
The official website for the RA4 paper and chemistry channel is this one:
https://www.originalphotopaper.com/range/photo-papers/
This website is actively maintained by the business unit that markets the papers and oversees its manufacture. The US website is maintained by the American business unit which is not directly related to the paper business, other than that they act as an internal customer.
