A property launch needs a walkthrough. A B2B manufacturer needs a two-minute explanation an export buyer will actually finish. A campaign needs vertical video cut for the feed. These are different formats with different rules, and treating them as one deliverable is why so much corporate video goes unwatched.
Because we also run the campaigns and build the sites, creative gets produced against a distribution plan rather than handed over as files. The aspect ratios, the opening three seconds, the captions, and the file weights are all decided by where the piece is going.