The CRS804 looks interesting but it also shares the characteristic of CRS812 and RDS2216 that it's long enough to require rear support but the combined length of the device and the included rear supports is not enough to reach the back of a full-depth rack. Which is what you'd need in the "AI cluster" use case they tout.
Also, typically these two-switches-in-1U setups (like from Dell and NVIDIA) are intended to provide full physical redundancy, and those vendors provide a mounting setup where there's a sort of a 1U cage with two slots the switches then toollessly slide into. The problem with the MikroTik approach is that you can't replace one of the switches without removing both from the rack (at least if the RMK-2x10/19 is used like in the promo video), so that really reduces the redundancy provided.
The price is a fraction of the others too, of course.