When creating a Compose action we can add an input. However, we can not give the Compose action a name (you can rename the action of course but not type in a name next to the input field). If you compare with variables - for variables we can set a name.
I want to use Compose actions in order to make my flows easier to read, follow and find errors if the flow has not run correctly. But when you use the output from the Compose action in a later step in the flow there is no way to see from which Compose action the output comes from (only if you hoover over it, then you can see the name you set for the action under ... and rename).
Compare this behaviour to how variables is presented at later steps in a flow - then we can see the name we set for the variable instead of "Outputs" which is much better for the readability.