It's not that high end retouchers don't use Frequency Separation but they do it far more sparingly than what you see in most entry level retouching tutorials.
The pros really just do dodge and burn so you maintain skin texture much better. Frequency Separation would be more for problematic areas like creases in armpits or necks come to mind. It's sometimes called "Texture Grafting," and you can find tutorials on it by searching for that.
Sidebar -- How to Texture Graft:
- Make your LF and HF layers
- Duplicate the HF layer
- Change the top HF's blend mode to Normal but then clip it to your original HF layer (which is set to Linear Light)
- Then using the top HF you select areas for duplicating, copy, paste, move, rotate, scale all of that to position it over large blemishes. Then apply an inverted mask (hold Alt while clicking the mask key) and then gently paint that in just over the blemish.
In doing it with this type of method you're reducing the loss of detail to only the areas really needing the copied texture.
You can, and should use Frequency Separation, just sparingly and when necessary not as a one-click solution which will result in horribly alien looking skin. It's important to remember what Frequency Separation is really doing and the different ways it can be used. For example if you want to check colors it might be helpful to look at your Low Frequency layer without texture to get a better idea of how well your colors are blending together. But for most things you'll get better results using simple Dodging and Burning on Curves Adjustment Layers. You'll also end up having more control as you can easily clip to those if you need to do more localized adjustments after.