Editing outside of pro plan

I am confused as to why a user is restricted to editing on a pro plan ONLY when they have a license on the same plan. This seems counter-productive and restricts someone to only collaborating with one entity.

For example, I want to grant access to edit within my sheet to another user who is part of an organization with their own Smartsheet license--- I simply can't?

How does this promote collaboration or reduce workload for our staff? It restricts other collaborators to view access only, makes our team work more to update sheets and causing them to send out request for something that could be more easily automated.

This setting is simply Anti-Collaborative and seems to serve no useful purpose for a small business with multiple vendors...who needs to collaborate.