Most / all consumer diagnostic tools are read only, often pull DTC codes from the vehicle. There are a ton of other stuff you can do with UDS for example. Maintenance resets, actuator testing, coding, all sorts of other stuff.

An example I recently did with my car was disabling auto start-top. not possible with consumer tools. Another simple one is maintenance resets - some consumer tools can do this. ABS bleeding - often you can't do it with consumer grade. etc.