No one said it's been done. There has been healthy debate about the fact that there hasn't been any (major) new social media networks since Snap (and Instagram before it). The cloud computing paradigm is now mostly dominated by 2 players (with GCP a distant third). here are 2 major desktop OSes, 2 major mobile OSes. etc.

This isn't proof that it won't happen again, it just says that the rate at which new innovations in software (and a new workout app doesn't count) has slowed down. LLMs being the exception but it's not like you and I can start an AI company in our garage.