The upside of the `Like` representation over the custom activity representation is that reactions can at least be interpreted as plain `Like`s even if the recipient server doesn't fully support the reaction feature.
The downside, on the other hand, is that, well, the reactions are interpreted as `Like`s if the recipient server doesn't support the reaction feature, even when the reaction doesn't bear positive intent at all (e.g. the thumbs down emoji: 👎).