As for your system, you're forgetting about maintenance.
Having a 2.5% advantage means that you can maintain only 2.5% more ships. You can replace losses slightly faster too, but those values are insignificant compared to tactics and strategies and terrain.
If you spend resources building BSYs, then you'll have less available to build and maintain ships. Bases cost maintenance too.
In some mods, BSYs are important. But you still have to balance your Yard investments with expansion and defense.
You will learn these lessons if you play against the experts.
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c_of_red said:
One battle does not a war make.***
In that particular case, I'd say one battle doth a war break.
With half our respective navies now crippled, neither of us could scrape together enough ships to breach the other's warppoint fortifications. At least not for a year or two, and without leaving other areas of the empire dangerously unprotected. Once we've had time to regroup, things may heat up again.
PS:
It sounds like you might want to write yourself up a super-gritty-tech mod, in which armor and shields are absurdly expensive, and naked ships are the norm.
However, such a mod would make strategy and tactics even MORE important, since the first shot wins.