I agree with the sentiment in a sprint basis. But after 20-30 (hopefully less) sprints some patterns start to emerge out of the metrics and some consistency builds up in the team or teams (because every team is more or less an atomic unit, so it sort of “scales”). Those are imo the real advantages. You could say that there are other methods with which you can gather patterns, build up consistency and scale an organization but I don’t know of any method as straightforward and simple (although very faulty) as agile.
In a startup with 3-4 people is obviously most of the time not a good idea to stick to all agile rituals, but even in a small organization there are things to mimic from agile processes.