That's a fair point. I think it would matter only when the company in question has decided to share common tasks (like a bank account, or even a user database)

That's a fair point. I think it would matter only when the company in question has decided to share common tasks (like a bank account, or even a user database) across all of their projects. Quick decoupling or forced encapsulation of projects seems to be a consideration that should be built into a company with more than one product.