i love privating my steam profile like...you're not looking at my tf2 hours lmfao
more practically speaking, it keeps away scammers and makes sure people irl can't happen upon your hours/2 weeks without u knowing.
also keep in mind a that a lot of private profiles are just on "friends only", also that i'm pretty sure valve made private default in the past couple years, so normie or old accounts are private much more commonly