I get dec points through the "achievements" but the extractor which is supposed to give dec points does not ? I extracted over 20 heroes with no gain. Is there really no way to gain more points ?
There's the few "achievements" for extracting heroes, but otherwise it seems to have no use once you've hit the cap on that particular "achievement."
There definitely seems to be a limit on DEC points and it feels pretty low after around the start of chapter 2. I personally find it especially annoying that I have to spend DEC to get DEC in a lot of cases (unique rooms, traps, and unit types).
The deal with limiting what you can do is about choosing to go for example fire or frost, its about trees where you can't get to the end of all branches, in Impire having that kind of limit simply means that you will never use certain aspects of your base, never recruit certain types of units and all those runes you can choose from.... you can't afford to pick them. If it is a design choice it is a poor one.