Welcome to the Forum @Kristen_Hughes 
and thank you for reaching out!
You are correct here. When a Form is submitted, the Project Members don’t receive an email notification even if they have enabled to receive Email notification for Activity updates. The only member that receives an email notification is the assignee of the Task that has been created.
However, you do receive an Inbox notification for this new task that has been created through the Form Submission.
I’ve gone ahead and escalated your feedback for our team to consider this; I’ll make sure to keep you posted as soon as I have an update on my end.
Have a great weekend! 