Let's assume the following scenario:
I have a sales organization with multiple regions. Every region is represented in a territory using Territory Management. The accounts are assigned to those territories based on the account's region. Accounts and opportunties are Private OWD, so sharing is done through this territory.
So far so good.
When opportunities get into a certain stage, I want to give access to a special team (specific for that region), that only needs access during that stage, and should lose access again when the opportunity moves further. Let's assume this is a manual process to keep the scope of this question small.
I was thinking of using the Opportunity Territory field for that, and have a separate territory holding the users that are part of this special team. However, when I assign this territory to the opportunity and go the the Sharing button in classic, I notice that not this special team's territory gets access, but its parent.
This seems to be working as designed according to the documentation:
When you assign a territory to an opportunity, that opportunity is shared with all Salesforce users assigned to that territory’s parent in the territory model’s hierarchy.
I just cannot wrap my head around the logic behind this. Perhaps I'm missing some essential part of the sharing logic behind Territory Management, but to me it doesn't make sense to assign it to the parent territory instead of the territory itself.
What is the reasoning behind this?