A a counterclaim is included in argumentative writing to

Counterclaims are included in argumentative writing when attempting to develop a persuasive argument towards a specific claim. By targeting and accepting the counter-argument as logically valid, it provides more legitimacy and credibility to the argument that is being persuaded.

Basically, what you're saying is "I know about the counter claim, but I still stick to my opinion" - this makes your opinion stronger, since it also stands up to its possible criticism.