I get that, but imagine someone new to the hobby picks up the latest box set, and grabs a nearby army book. Doesn't realize till later he has the rulebook for one edition, and an army book for another. There is no way from looking at the products to know which goes with which if you weren't more into the hobby.
I certainly hope anyone joining the hobby would at least research or inquire at the store what to get before starting. Plus in this day and age, most people I know would look it up online before purchasing (usually to see if its cheaper on amazon). But your argument can be made by someone buying an age of sigmar rulebook, then an adeptus mechanicus army book, and Chaos space marine models. Hopefully the meatspace store has it all organized but unless the customer asks an employee, they may not know the difference. I put that burden on the customer, its their money thats being thrown around
And some rule editions make certain units more powerful across different editions and points go along with that. So if you have a codex of an army which is great at close combat, and you pay a premium for units that excel at that, but buy a rulebook that makes close combat less effective, then you are overpaying.
Or some rules might conflict too, or use different terminology.
True, but most first time explorers into the community don't usually go after whats powerful on the tabletop, they usually go after what looks cool. Its more fun to have models you think are cool on the tabletop than being a powergamer (at least when you start). But everyone gets their fun a different way. Some just like to paint, some like to play fun games, and some like to play competitively.
But its an interesting though. I don't think I've ever heard of anyone having a problem like that.
Same here. Considering how expensive everything is, you'd think people would research or at least ask before purchasing. Its hard to return model kits that have been glued together already.