It should be though and I’m sure there’s lots of users, including me, who would appreciate it. Maybe not the specific case which OP addressed, but other instances like not having related history-entries show up while typing something into the address bar. Here’s some scenarios in which it is needed:
You’re doing a presentation for colleagues/fellow students and you have to show something on the web. Don’t want embarrassing sites come up.
You’re in the library or on the train with your phone/laptop. Same scenario.
You give your phone to a friend so he can enter a site he wanted to show you (happened to be recently).
You’re at home and a friend is visiting and you let him use your browser (i.e. to show you something/to look up his bus departure times/whateverthefuck)//you want to show something to your friends and start typing in the address bar.
As demonstrated, giving the options for IRL privacy precautions would be helpful for many different people in many different scenarios. Please consider.