There's one element I'd like to add to this discussion. It's format size and its relationship to soft focus images.
Frankly, I don't think 35mm soft focus photographs can approach the quality of a large format soft focus print.
A 35mm soft focus print will still have sharp focus grain. To blur the grain pattern requires the picture itself to be blurred and there is a world of difference between soft focus and out-of-focus.
This sharp grain/soft image creates, I think, a discordant image. The viewer is confronted with seeing a soft focus image and simultaneously a sharp grain pattern.