That's a common misconception. Seeds aren't hot at all. However, the membrane that the seeds attach to is the hottest part of the pepper so if they let the seeds rub all over the membrane when removing them then taste them they assume that the heat is coming from the seeds.
Hmmm. I always pull the seeds, lately, for growing the following year. This has been the best year so far for growth. I probably bought these at the store at least 2 or 3 years ago. Just keep recycling the seeds.
I usually pull the immediate flesh with the seeds so I must be taking that hottest part out (and letting it air dry).