I think in some cases it is a form of abuse. I'm also disgusted by the fact generous fit kids clothes are so readily available in many places, given that standard fit has become so overly generous. You'd think the minority of kids with a genuine reason to need extra width would be like petite and tall ones- too small a market to be readily available.
I think the puppy fat/ will grow tall line is often bull too. If there is a family history of it, fair enough. But when most adults in the family are overweight and/or short, it should be a wake up call.
I don't agree it's an excuse to say they all eat the same either, we're all different. My stick thin 12yr old eats more than many 6' men, if I gave her the quantities her healthy friends eat she'd be emaciated. And if her friends are what she did they'd be huge.
I think with kids though concern should be about what habits and attitudes they are learning, rather than whether they are a bit chubby or not. The skinny kid who eats for pleasure/ boredom, with small portions of junk at mealtimes, no exercise and overweight parents will probably become an obese adult too. The chubby kid with slim parents, eating a normal healthy diet, but only eating for hunger, not greed, with an active lifestyle, probably will even out.
However, given the trend for following toddlers and young dc about and offering snacks every 5 minutes, I suspect there are a hell of a lot of kids who have no idea how hungry, and therefore full, feels like, and are being taught to eat for the wrong reasons. Alongside the trend for teaching kids to sit around all day.