Based on the shared experience here, it can work, but only in limited situations. The strongest results seem to come when the subject is already clearly separated from the background, there’s some shallow depth of field to begin with, and the subject edges are simple. In those best-case scenarios, the effect can look fairly convincing.

Where it tends to fall apart is with difficult masking, especially things like long hair or other fine edge detail. In those cases, it may require a lot of manual Photoshop selection and cleanup to get acceptable results.

So it’s probably not just a gimmick, but it also isn’t a reliable fix for every image. If your photos already have good subject/background separation, it may be useful; if you want it to create realistic bokeh from complex scenes, expectations should be modest.