I advise against assigning resources to summary tasks for sure. But, we actually have the opposite problem in that people are reluctant to actually assign resources to tasks. So, this actually gives me more ammunition to let them know they need to assign resources in order for their calendar to work.
I do know part of the reason is PM’s would like to publish the project every time a small change is made to a task. The entire team receives the update e-mail whether their specific task has actually changed or not (since every task gets modified on a publish). I have read on here that this is expected behavior and its something we just have to live with. But, it does make PM’s more reluctant to do the assignment and we do not have any governance in place yet to require it.