When I learned about VCA mixing, the first thought I had was - "Wow, if I ever plan on using groups at all, not having VCA control would be a serious limitation."
The primary problem is that a group fader does not affect post-fade sends. If I have backing vocals grouped with a little bit of reverb on the aux send, when I lower the group's fader I'll still have the wet effects signal at the same level in the main mix. Alternately, I have aux-fed subs and the drums grouped together. When I lower that group's fader, the sub is still pumping at same level despite the signal from the drum mics being lower in the main mix.
In both situations, you would need a second hand to change whatever is being aux-fed when you move the group fader. But how do you know how much to change it when you move the group fader (other than by listening)? Is it being fussy to say that this is an unacceptable lack of control? In most of your experience does not the absence of VCA not amount to a problem?