You might be confusing softbuffer for minifb here, as softbuffer doesn't do any window handling of its own. All window management and event handling happens through winit (or another crate providing a HasWindowHandle implementation).
Yes, exactly this -- it's a fast and convenient way for my code to just write the pixels into a spot in RAM (the CPU's RAM, not VRAM) and have those pixels end up on screen. On modern architectures this nearly always goes through a GPU, so even if you're not using the GPU to accelerate your 3D rendering/math, you gotta deal with it just to put pixels on a screen at the end of the day. So that's what wgpu does for me.
(I originally wrote this a few years ago but other people maintain it now)