One issue is heterogeneity in effects across individuals. Even with traditional antidepressants, it's common for people to respond to one drug class but not another. So it's conceivable, just based on this study, there are people who might respond to psychedelics who might not respond to other things, and vice versa. So even if the effect in the general population, on average, is the same, it might be useful for a different subgroup, which is still differentially useful.

I suspect a lot of these effects have been overhyped, but the same could be said of any depression treatment, and there's good evidence for a lot of treatments even if the effects are smaller than they're sometimes made out to be.