> To be fair, it's possible that software never was the moat

This is the answer to all of your questions. Network effect and brand recognition sell Oracle, Adobe, office etc. Alternatives to all of them already exist, with either feature parity or close enough for most people.

The existing brands keep going because big companies and institutions don't pay for products vibe coded by some guy in a garage, they buy products that have paid support that they know will continue to exist for years.