I'm reading this as less of a gripe in GA not having a ROI report and more of complaining about marketing attribution. Marketing attribution isn't a super-easy

I'm reading this as less of a gripe in GA not having a ROI report and more of complaining about marketing attribution. Marketing attribution isn't a super-easy problem to solve. But complaining that GA doesn't know that a person saw a Facebook ad at some point before ultimately subscribing (and interacting with more ads along the way) is a bit like complaining that your car isn't also a boat and plane. If you want comprehensive analytics, you need to spend time developing a comprehensive measurement plan and then spend time doing the reporting. Expecting any tool to do precisely what you want, despite the tool neither claiming nor even desiring to do what you expect, isn't a plan.