Thats the only measure of real profitability - GAAP.
Free cash flow includes stock based compensation. Thats a real expanse and turns negative cashflow to positive. But it dilutes existing shareholders, you would like to see positive cashflow EXCLUDING stock based compensation
If GAAP is the only measure, then Amazon and Salesforce have been utter failures for 20+ years, only returning 120,000% and 4000% returns to shareholders.
In fact, if an investor went by GAAP, he would have missed the entire massive SaaS boom of the past decade.