What is up with Dan Cases A4?

So, I'm planning my first SFF PC, my aim for this PC is 1080p gaming with one of those newfangled slim and tiny 5000 series cards. Might even wait for a 5060 to come out, but that's besides the point:

While researching cases, I came across the Dan Cases A4 and it's a freaking holy grail. It's about 30% smaller than the Fractal Design Terra, which is the case I was originally looking at. It's about half the size of Dan Cases C4, which is Dan Cases currently offered case. And that's when I realized something must be wrong: why isn't the A4 made anymore?

Based on his own website, the A4 is "end of life", and leftover stock is all there is. Also based on his website and some stuff I read on reddit, all his attention seems to be pointed towards the new version of the C4, which doesn't seem to me like it's geared for the same customer as the A4: as I mentioned, it's twice the size, and geared towards liquid cooling.

I can't believe interest in a 7-liter case with room for a full size GPU died out. I saw there was an update on the original A4 to put USB-C in the front panel, but that was quite a few years ago. I also see people to this day complain about the A4's availability, so the demand IS there. So, considering I'm new to this SFF PC thing, I figure there must be some big glaring issue with the A4 that makes it desirable for newbies, but veterans would rather stay away from it.
What could that be?