There are lots of situations where USPTO will refuse to do what you want if USPTO thinks that you are not the “attorney of record”. Filing any of a variety of EFS-Web auto-granted actions such as a Terminal Disclaimer. When you try to do any of these things in an application file, the EFS-Web system asks you to type in your registration number and will look up that number in the Palm database for the application file. If EFS-Web thinks you aren’t the attorney of record, it will halt and refuse to let you move forward.
As another example it is impossible to get the auto-granted petition to withdraw as attorney, unless the Palm system thinks you are the attorney.
You never know when one of these situations might come up without warning, and you would need to get such a filing done. Which means that as a general rule you should be filing a Power of Attorney in each case. And as a general rule you should docket carefully to check to make sure the USPTO actually recognizes the Power of Attorney. Then when a crunch time comes, such as the need to urgently file a Terminal Disclaimer, or get yourself withdrawn as attorney, you will actually be able to get the task done.
And as it turns out, at least two of USPTO’s ways for you to supposedly learn whether or not the USPTO recognizes the Power of Attorney are flawed and can’t be trusted.