As you know, there's no feature for that yet as that will be hard to implement. Mass Planner will require to check all of the posts of an account before it follows the account, causing for delays. We will be receiving a lot of emails on why their MP is not following fast enough and is taking too much resources.
However, we will see if this can be implemented in the future. If a lot of users need this feature then the devs will surely consider it.