Sorry, I thought the rest was implied. Because the company also sold user data (and stated that in the T&C's). The industry is very aware of email aliases and so it is more valuable to have sanitized data.
I used to work for a product comparison company (think finance and insurance). We used to save the email address as typed for login and also with everything after the plus removed separately. For Gmail and certain other large providers, we also stripped out any dots e.g. a.j.uniquename@gmail.com became ajuniquename@gmail.com.
Took me far too long to realize that there is a kids version of the kindle that you were talking about, and that you weren't just referring to other users as kids.
I agree. It's a good rule for a larger community, but I think being enforced so early will only harm growth. And yes, I know growth is not necessarily the main goal - but we surely want enough initial growth to hit that critical mass that sustains a reasonable level of activity?
I'd rather not dox myself. They're not a huge company. I promise you that this is not something uncommon.