The Twitter app written by one guy did not have scale, analytics, reporting, advertising, compliance, or moderation features.
Engineers are constantly surprised at how necessary it becomes to do those things as a company grows, and how hard it is to do them well. Musk himself has been repeatedly surprised at how hard it is to scale operations efficiently, at both SpaceX and at Tesla.
Remember the twitter app was originally written by one guy - I bet that team has 50 people on it now, and it’s not better for it.