This is not the post I read last week but I can't seem to find it again. it's a shame, because it was explained in layman's terms in that one.

This one is the most recent one I found. It's still a little (or lot) technical, but maybe it can help you to understand a little more.

https://steemit.com/steem/@lukestokes/if-you-hold-steem-power-you-re-earning-steem-automatically

Wait, it might have been this one:
https://busy.org/@preparedwombat/46zsyy-the-steem-power-you-earn-for-holding-steem-power

but I'm not sure.

Try searching for 'steem power interest' or 'steem power inflation'. There has to be someone who has ever published a post that was understandable for non-techies too :0)