@Arjun sir, I think address translation is not necessary for providing memory protection. We can also achieve this using "Relocation and Limit register mechanism".
"When the CPU scheduler selects a process for execution,the dispatcher loads the relocation and limit registers with the correct values as part of context switch.Because every address generated by the CPU is checked against these registers,we can protect both the operating system and the other user programs and data from being modified by the running process."
I think "only" for he purpose of memory protection if we use PT then it will be overhead while context-switch due to the large size of PT(while less overhead in limit and relocation register).
@Arjun sir, can you please check this.