I’m quite comfortable with the concept of depth of field and use it quite often to emphasise the fore ground or the background depending on the style of images trying to produce.
Here are a few examples of how I have been using it:
Here I am attempting to use a short depth of field to emphasise the bud in the centre and to trying to reduce any distraction in the background.
Here the focus is on the distance so the foreground I used defocused to force the eye to the brighter part of the hill and the sky.
Here I have added a software depth of field blur to act like a Vignette. (Affinity)