I don't know enough about how different profiles operate to say with any certainty, unfortunately. So it's possible there is no benefit. However, for mobile there does appear to be at least one benefit. When I recently checked to see what data Google had on me using their free tool, I saw that the only web history they had associated with my device was all from URLs visiting while not in privacy mode. These were all links that I clicked from text messages which will always default to open in the regular, non-private tabs, even if you only have incognito tabs open. That right there is enough for me to always and forever use nothing but privacy mode. For the PC, this is a non-issue as I never log into my browser. Although I do use privacy mode there near 100% of the time as well.