Mirai did have soft selection, yes. You had to define its radius by selecting elements on the mesh and it was pretty fancy from what I remember. Surface- or volume-based depending on your choice, lockable too - I think. 3ds max gained these features over time. Maya had its soft selection tools revamped at some point, not…
The actual models that go into animation are still done like what's shown in the OP: manageable base model created in a very clean way by whatever method most suited to the shape required and/or defined by what the software supports - and then subdivided as needed. What's changed is the complexity of everything going into…
Per-pixel displacement at render time was a thing long before sculpting and definitely used on these late 90's and onwards films to detail surfaces. Pixar Renderman had it pretty early IIRC. So what you needed was a displacement map that contained the detail you were after. You could paint that in Alias Studiopaint onto…