I think it depends on perspective. There is not evidence that surgical masks useful in preventing someone from contracting covid [0]. Which makes sense because droplets can still be inhaled because air flows around the mask (unlike n95 respirators).

Masks are very useful in preventing spread, thus useful for overall slowing the spread of the disease.

[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7118603/