It's actually very hard and expensive to do end-to-end reporting, so it's not as simple as you either prove profitability or not. Think of how many SMB's there are out there that have to choose between hiring a new service provider to provide better coverage or spending money on an obscure-to-them tool like a CRM. I feel for them.

In addition, time is always an issue and is the ultimate variable. What worked two months ago didn't work last month, what do you do? Every company runs into this and there are factors that make it crazy complicated: payback period, LTV, AOV, Days to Close.

Ad platforms like Google Ads and Facebook Ads talk more about "reaching your target customer" with fluffy metrics since that's what they can easily measure and, IMO, it obscures the real end-to-end results you mention. When success is obscured, it allows them to absolve themselves of educating their customers.

The ad platforms build case studies of success and then simplify it down to impressions and reach so that companies feel like they have to do it. It's a profit machine.