This is specific to the idea of using a backend workflow as a webhook, so if a API call is received, we can configure that to have a user unique ID value passed in, whether as a parameter or in a similar way as an Admin API Token would be…having the user unique ID as another parameter or similar to Admin API Token would just provide the ability to run as the user without needing email and password to be sent through.

The fact that backend workflows often have more parameters than just user doesn’t in any way affect the usefulness of the feature or alter the practicality…unless I’m missing something from your point, which I summarize as ‘because there are often many more parameters than just user, it is not practical to be able to run the workflow as a user’.