I hear this a lot, but I've never actually seen any proper testing done on this.
Personally, I think the early stuff (Digitech 2120, etc) wasn't good enough. I did use it (and loved it when gigging for exactly the reasons you outline) and it was great, but there were some elements of it that weren't as good as the 'real' thing. Ironically the Wah was the weakest part of that particular rack unit, and it was the only analogue thing in there!
However, now I don't think there's any reason why you'd take the stomp boxes over a Helix. I've done some back-to-back testing with some of the pieces of gear, and I can't tell the difference.
I agree about editing - it's certainly not the same experience as a bunch of pedals, but in every other area, it's a no-brainer for me, including in the studio.
I mean an old friend just linked me their bandcamp. It has a few dozen songs that sound great. Turns out half were made with only a Kaossillator Pro. The other half with only an original Kaossillator.
Working that way wouldn’t work for me, but it works for Sy. And ordinary folks would say that’s a poor way to make songs.
In a studio, I'll use a good modeler all day long. Going direct and modeling in the box is the best - you can change your virtual amp and cab after recording to get the perfect sound/mix. You would never be able to tell the difference in the right hands.
Blind experiments with long time musicians keep showing this claim to be flat out wrong, over and over.
Playing on a Kemper with a Helix, when set up properly (and that's hardly a science anymore, tons of people have done the preset tweaking for us by now), is simply indistinguishable from analog.
It's actually the opposite. Modelling can absolutely reproduce any audible effect you can find or imagine.
What is true is that, for any specific effect or device or technique, there probably isn't a ready-made model for it. Or there is, but it's for some variant of the amp that the software author used and not the one you want. Modelling is expensive in engineering time.
But if you just want a stable of high quality effects from which to assemble audio for recording or performance, analog junk frankly has nothing to offer in the modern world.
For a touring musician the modeling route is just WAY better. Recalling your sound night after night without working with sensitive and fiddle equipment great.The bottleneck for sound quality is always FoH and never your rig. A Kemper or helix is the better option for nearly everyone.
That being said, I wouldn’t ever use modeling in the studio. Stumbling upon a great sound when exploring doesn’t happen in the same way. Editing patches becomes a chore and analysis paralysis becomes a force of destruction.
Recalling that sound in a live setting though…