Why should we not use the waterfall model for software development?

In engineering, we learned about the waterfall and its software development phases that are gathering requirements, analysis, designing, development, testing, deployment and maintenance. Where each phase has its unique roles and responsibilities. Without taking too much time explaining this model I should jump into its drawbacks that are a niche.

Drawbacks:

1. It is difficult to revert back to the previous phase if any mistake happens.
2. Waterfall teams are not as flexible as agile teams.
3. After the crucial phase (requirement gathering) of SDLC. It becomes difficult to monitor the progress of software development. If a client wants to check.