I remember when a candy bar was 1/2 today's size. Everywhere you go it's "supersized this" and "supersized that". Even snickers bars are 2" longer, 1/2" thicker, and 1/2" wider than they used to be.
Perhaps, I haven't purchased one since I stopped doing packaged foods, but I no longer notice the standard sized candy bars, the liquor store counters and grocery store check-out aisles seem to be filled only with the "king size" versions.
I actually noticed the opposite. A few days ago I had a craving for a snickers bar. I haven't had one in years. So I popped into my local 7-11 and I noticed that the candy bars all looked...smaller... than when I was a kid. There was no king size to be found. Anecdotal? Sure, but it does support what the poster was claiming.
Your point of reference has changed. My father was the biggest man in the world when I was 5 years old, now I feel like I could hollow out a leg and hide him in it.