Grosnak
Quick release axles are much stronger, gauge for gauge, than solid axles.I’d be surprised if you could get a cassette hub with solid axle as they are pretty much downmarket items.
If you are talking of specialist MTB downhiller axles, which are very thick indeed, up to 20mm, well that’s a differant matter, but the problem here is that such axles also need the frame that can fit them too, this will add a serious cost.