According to industry analyst and insider Mat Piscatella, Sony-published Helldivers 2 is such a huge smash hit that it eclipsed every other title, including perennial bestsellers like Call of Duty, a multiplatform release, based on sales on PS5 -alone-.
This puts to rest any fearmongering that any title needs to be multiplatform to be successful. Platforms that games launch on are based on a calculus that each publisher decides, and going multiplatform does not guarantee success and being exclusive is not indicative of lost sales.