They are, but you've still only got so many to go around
4x for the PCI-E 5.0 NVME is mandated I believe.
16x PCI-E 5.0 for the Graphics card
which still only leaves you with 4x PCI 5.0 lanes (or 8x PCI-E 4.0 or 16x PCI-E 3.0)
Even if lanes end up being split/reduced to lower speeds, then it's doubtful they'll be many boards that do, as it'll incur additional cost with splitter chips and the like
It's also down to physical board space! Saying that I've used a lot of the ASUS Creator boards in builds and they are about the same cost as an equivalent 'enthusiast' board, but with actual useful features not just RGB and LED screens all over it. The new X670 Creator has 3x 16x slots which can be split into 2x 8x PCI-E 5.0 and one 8x PCI-E 4.0, or it can have 1x 8x 5.0 slot, 1x 4x 5.0 slot, (with 2x PCI-E 5.0 NVMe's) and then the 8x 4.0 as well as that. A bit confusing, but it works well if that is how you want it.