Salesforce DX offers the developers an option to custom code the apps locally and then first deploy it to Sandbox Org or Production Org from the command line interface. Bust as any expert developer may think, no development process is complete without a source of truth.
It is okay to make any changes in the IDE of your choice, but what will happen when multiple developers work on the same file simultaneously? What may happen if someone makes a change in the code and want to revert later? So, if there is no single source to track and manage the