Why don't more amp heads use true stereo?

I've had a Gerlitz Revelator, which had a stereo FX Loop and the ability to drive two cabinets in true stereo. It was my first real experience with FX loops, and I loved what I could do with it. Since then, I've only found Diezel Amps that can do this, and I'm wondering why more companies don't use this idea. I get that I can just do virtually the same thing with a simple poweramp in conjunction with whatever head I'm using, but I'm concerned about the tone being affected and hey, it just looks cleaner from one head. Thoughts?

Is the VH4 true stereo?


It's not dual mono? Does it use a comb filter?

Papa?

VH4S has two 50 watt power amps.
If you have a stereo effect unit it´s true stereo.

This is similar to the Rivera S120 (two 60 watt power section) with stereo/chorus.