Salesforce is really just a cloud based database with a UI slapped on top of it (for both administration and end users).
- New Tables and Columns can be added via a Web UI without any downtime.
- Business processes can be automated using custom "apex code" (a ripoff of java 1.6) and "visual code" workflow engines.
- UI/Layouts can be customized via drag and drop editors and a "Web Component" framework (LWC).
- The user security model is robust (Record level access, Field level access & record sharing rules)
- There is a pretty solid REST API that is updated in realtime to reflect your models.
- The entire org configuration is defined as deployable "metadata" (XML).
All this makes it extremely easy to model business processes and quickly build business 'apps'.
However, building anything of significant complexity becomes extremely expense very quickly. And once you've built critical processes into salesforce, you are forever vendor locked.
The Salesforce Account Manager's goal is to raise total subscription cost 7% with every contract renewal, even if your needs have not changed. They can typically accomplish this by offering your free features early on, letting you become dependent on them and then taking them away if you do not pay more.