For the record, older players also sometimes miss out on certain things too. It's not just the newer players. For example, I saw someone with 5000+ hours wearing the horns.
I don't think it's a big deal if they occasionally re-sell a couple old hats that were originally sold in a hat shop for a long period of time. These hats are more "old" than they are "rare". If they were to re-sell hats that were sold exclusively at revolution or nexus a long time ago, or old hats that were really expensive, that would be a different story.