Like most electronic parts, failure is usually early or never. Which is why 8 year warranty is good protection and infant mortality 3 batteries (if any) are not worrisome. You have much higher probability of totaling your car in accident than the tiny risk of post warranty battery failure.That would be unfounded paranoia. However that isn't what is happening here though. It isn't assuming the need, it is assuming there is a risk of a need.
To claiming otherwise is another way a stated that the battery failure rate is going to be zero. We know with the Model S & X that isn't true. I'd be quite surprised if there hasn't already been a Model 3 [infant death] failure.
If some people want to fret about very low probability risk that’s Their decision. I just don’t like to see those who come to this forum to learn or make buying decisions put off by paranoia.