Crank sensor replacement

Please help. I don't understand replacement procedure on crank sensor. The new sensor has 2 elongated slots for adjustment why couldn't I mark old one before I removed and simply replace it. Then no adjustment in and out towards drive plate so why need alignment tool. Need to play with timing with timing peg and alignment tool 2 special tools plus a metric bolt. Is all of this necessary? I know on gm do a crank relearn with scan tool but I never played with timing before cps replacement before. How does pcm know it is replaced? What is the pcm looking for? I know it looks at crank cam correlation but just replacing a hall effect sensor. I don't understand why have to do this lengthy procedure. Please explain I would deeply appreciate it.

Forgot to mention 2014 Ford focus 2.0 engine

Pictures would help. I have never done this job on this vehicle.

You don't want too. It's a Ford thing. Wanted to know if anyone has ever replaced one without doing timing peg and alignment tool? If you get a chance look online ford 2.0 ecoboost engine cps replacement.