An Amiga with no boards installed is unstable, so how is it that different?
Crappy software and not the hardware, perhaps. I tend to rely upon people like Piru and Jens as authoritative in their specific realms, especially when given salient arguments for their positions.
Aside from that, when people spend a shytload of money on hardware, they expect it to work properly. I had an Apollo accelerator in my 4000D and it caused all sorts of problems with various other devices. Move to a WarpEngine then to my CyberStorm and neither one ever just crashed due to hardware and I cannot recall any incompatibilities I've had with either.
In any case, Jens owns the rights, he's spoken out numerous times on the issue, and I find nothing wrong with his position on the matter, irrespective of dreck anyone may boil up about him trying to kill a product to further his own.