The core tradeoff here is "Push vs. Pull". Webhooks are a model for pushing data to subscribers. A traditional API allows clients to request and pull data. The data flow is in the same direction, but control flow is opposite.

Push-oriented models are much easier to reason about and should be preferred where possible (cybernetically they are a closed loop, vs. push models which could literally just be a barrage of UDP packets). But they do have a little bit of overhead which makes them the wrong tool for some cases, like live-streamed entertainment or massive telemetry flows which value performance (latency, throughput) over missing a few packets.