Your first point -- that you can be easily killed or checkmated by a sufficiently powerful program regardless of how it is implemented -- is true but irrelevant: the question was not whether the program is powerful and effective (which I would not dispute) but whether it deserves to be called intelligent. You can say that whether it is intelligent or not is unimportant and that what matters is how effective it is, but it is wrong to conflate the two questions and pretend that an answer for one is an answer for the other, unless you are going to make an explicit argument that they are isomorphic or equivalent in some way.

I would argue that a problem domain where brute-force search with simple optimizations actually works extremely well is a problem domain that does not require intelligence. If brute-force search with a few optimizations is intelligent, then a program for factoring numbers is an artificial intelligence.

I don't have a criterion for intelligence in mind, but like porn, "I know it when I see it". We might disagree about edge cases, but almost all of us will agree that a number factoring program isn't "intelligent" in any interesting sense of the term. That's not to say that it might not be fantastically effective, or that a similarly dumb program with weapons as actuators might not be a formidable foe, but it's a different question to that of intelligence.