Every recipe I can find on Google that isn't from a super-site with already strong SEO includes some sort of life anecdote. I find it hard to believe that:
1) This purported copyright trick even works, and
2) Everyone who publishes recipes online got the copyright trick memo, and
3) Everyone who publishes recipes online is interested in copyrighting their recipes as opposed to just having good ad revenue
I find it much easier to believe one of the following:
1) The life story section significantly improves SEO somehow, even if incidental. I'm not saying Google rewards life stories, but somehow there is a mechanism there that improves SEO, and people have cottoned on. Every recipe you're going find on Google has strong SEO, and hence every recipe you find has an SEO-improving life story attached to it.
2) Food bloggers include the stories for differentiation, to "build a stronger connection with their audience", and once a couple big ones started doing it, the rest followed.
3) Some sort of combination of 1 and 2.