Not true on 2 accounts.
#1, if the crank pulley AKA the harmonic balancer gets damaged for some reason( IE hit with a stick, dropped heavy tool, overtightened belt, or improper re-installation), the key way can get damaged due to excessive vibrations. I have seen this before on F2/FE/RF blocks that have never had the gear removed before.
#2, it's easy to get the required torque back on (116-123 ft/lbs as per the FSM) with a torque wrench and by putting the transmission into 5th gear. Another method is to make a 'block' to put between flywheel teeth and the trans bell housing at the starter opening. I've used thick steel and a friend made one out of a bolt and a series of washers.
Below is his write-up, paraphrased and shortened.
Here you can see how he ground down the sides of the washers and flattened out an area on the circumference of it also so it will engage into the flywheel teeth better.
Here it is in action, he held it with a 9/16" wrench just in case it popped out of the teeth of the flywheel, but it didn't.
yes, this was originally used to help remove the crank bolt, but just rotate it the other direction and it can be used to tighten as well.