Great essay! I have never played WH40k but have been quite into Magic the Gathering at times. Before I started playing I asked a friend what was to stop me just printing or photocopying cards (even in the 90s this would have been possible) I understood how silly that question was when I felt the pleasure of actually owning a high quality product. Sure, I could spend the time to make my own cards but playing the game…
One is the strong dependence on your peers for approval. If your group is against proxies, then you are screwed.
Second is that there are now more ways to play against each other online for free. This approach is much more convenient compared to creating proxies IRL and allows you to play with other people outside your peer group.