Actually I am pretty much confused how creation of users help! because if any one want to make a new user he will require my (real id password) when setting their own password using (sudo passwd username)! but my question is why should I tell them my password? On the other hand any one can get access to administration just by adding a simple (sudo group) as its secondary group! So if anyone get administration access so easily how security is ensured? Moreover what is the benefit of changing file permissions because you can do everything in root mode! And all admin users can edit my files which I have denied permission to.
as a beginner this few questions is puzzling me and I couldn't connect how those linux concepts are helpful! Hope I will get a logical feedback from community instead of getting some downvotes for this noob type questions!