Is that true for most modules though? Most modules spell out EXACTLY what each set monster will have as loot.monsters have treasure tables, adventures have placed treasure and items. While the DM can override those, having to do so to get a decent game from the books is not the DM’s fault however.
If the module's underlying expectations are that the group will mostly stock with these items, but there is also room/time/money for crafting and purchasing items, your very likely to have an imbalance that impacts play.