Inches aren't real. Laws aren't real. Language isn't even real.
Have you ever tripped over a line of longitude?
People live such abstract lives now that they're losing track of what is concrete.
On the contrary; I think. Nearly every definition disagrees with the claims you're making. It's not a mere synonym of "concrete" or antonym of "abstract".
https://www.merriam-webster.com/dictionary/real
And regardless, the usage here was clearly in the context of GP's (false) dichotomy between "real" or "false concept", so obviously the definition you're trying to prescribe doesn't apply.