That hybrid setup can deliver very satisfactory sound but for some guitarists, they also want real tube power amps because they behave differently than solid-state power amps.

The tube preamps give the distortion fuzz but the tube power amps also provide the extra dynamics that makes the whole response under the fingers more spongy, velvety, etc. Connecting the preamp outputs of a Mesa Boogie or Soldano into a solid-state amp has a different feel than tube power amps. The solid-state amp is definitely usable... but it's different.

That said, I sold all my tube amps and just use the stock digital emulations of guitar amps in Logic Pro. I got rid of almost all the analog gear that was heavy and required maintenance (e.g. new replacement tubes cost $200) because I didn't want it weighing me down as I got older.