I'm pretty good with photoshop, can do multiple exposures etc.
But I also own a set of Lee soft & hard grads and a set of colour temperature filters and I prefer to use them instead of 'shopping.
"Most would say medium format cameras are essential actually"
Not any more, the 5D is the least expensive digital equivalent of medium format film cameras and that's why
full frame is considered so important by people who consider that sort of thing. That and the larger photo sites.
Hard grads are useful for seascapes or where the horizon is, well, hard. Soft grads filters are way more versatile.
You can use, say a .9 grad to hold back the sky and an upside down .3 grad to hold back reflections on water.
It's generally considered best practice to get as much work done in camera, in front of the lens, in the field.