Seems I am missing a trick here, I may drop all my nice-to-have core internals and just fill up the slots with HRPs and a few MRPs, is that what combat cmdrs are doing?
While i generally don't set up my ships as extreme as Aashen, the game unfortunately currently very much encourages doing this. Health and resist stacking is way out of control since a while. FD ever so slightly tried to reduce it just on the shield side. Those who actually tested it liked the changes and many found that they didn't go far enough. But the community at large, mostly people who refused to ever test it or didn't even have access to the beta, went on a rampage and cried the changes away. Since then FD didn't dare to touch the subject any more.
It's the same story for SBs and HRPs. Drop in as many as you can afford, engineer them up, enjoy your ship being able to keep going despite taking insane damage. Many of the more fancy optionals you can use have counterplay. For example a reasonably good shot with a feedback railgun can neuter your SCB. But HRPs and their resists are pure numbers. The only counter for that would be adding raw damage. But people already engineer for high damage. And while you can enginer for an already insane +70% of damage output or more (without even looking at second effects like better efficiency, better WEP recharge, etc. ), this pales in comparison on how high you can stack your defenses. Stacked engineered HRPs don't use power. Which means you have more power left for engineered SBs. Which in turn also again strengthens your shields. The +70% of more firepower (which is already over the top) pales in comparison to +700% of defenses, which are all too common.
It's a problem deep in the design of engineers. Undoing this would need massive nerfs, just short of purging them with fire. But FD never had the balls for that, and the little courage they had for even ever so slight nerfs was eliminated by a part of the community who cried like little kids having their candy taken away.
That all being said: my ships usually run with less HRPs. I am not into PvP. The few times i accidentally launch in open, my setups have proven to be durable enough to make an escape. That's all i need. Thus i can afford to carry some of the more fancy toys. I find them more fun and thus still like to use them. Also note that the mentioned counterplay of other things is rare or nonexistant when facing NPCs. They either lack the tools to counter them or are extremely bad in applying them.