I'm going to throw in one of my most recent mods I've played with HOI4, and see if you think the mod makes the game "hardcore" or just excessively complicated.
Black Ice.
It's a mod which aims to keep the game historical, but adds significantly more "stuff". Such as making multiple types of infantry. Your standard units, garrisons, special units (ex, the SS), and a variety of other things. Each of them need seperate types of specialized equipment, including different shirts.
Does that sound like the Ops target of "hardcore" or is that just needless complication?
Consider in the base game. You make guns and train the men. In BI you need at minimum 7 seperate production lines to make a single basic infantry squad in most cases, and research requires that you keep your units up to date with the new required items.
Then, tank divisions are built using SPECIFIC tank models. So, you have Panzer 3, and then Panzer 4. The tanks aren't obfuscated together under the generic "meduim", but instead different entire productions which have different characteristics. Then, you have to maintain each piece of specific equipment for those tanks. You need to build armor variant radios, handheld radios, and mechanized radios, as well as HQ equipment to simulate long distance comms and encryption.
Is this hardcore or no?