In Shu't Avnei Neizer 381.2 he justifies the language of על ביעור חמץ even though לבער would seem to be more appropriate, as Tosafos and Ran already addressed. He says that the mitzvah of biur chametz is accomplished at the onset of Pesach. It is not a mitzvah accomplished at the time of biur, rather it is fulfilled when Pesach arrives after one has done the biur. And since once Pesach arrives, he has previously rid himself of chametz, it is more proper to make the blessing in a language that can also mean past tense, and not לבער which is only a future tense.
But we see that the mitzvah of biur is not to destroy chametz per se, but rather the insurance that one does not have the chametz on pesach.
At the end of Sh'a O'ch siman 432 The Ramma mentions the minhag to "put out pieces of bread to find during the bedika so his bracha should not be in nought. But if one did not place, it is not a problem being that all people have in mind when they make the bracha that they will destroy any chametz if they find it."
The achronim mention the opinion of Ta'z that one should in fact not put out these pieces as it can lead to problems if they are not found, and it is better to rely on the second idea in the Ramma. See Shaar Hatzion 11. Many uphold the minhag to put bread of course, and quote the Arizal to put ten pieces.
Again, in this second opinion of Ramma, we find bedikas chametz with a bracha, with no hope of actually finding chametz in one's possession. And no-one gives an eitza to go buy chametz, which would fly in the face of the Taz's concern which was said about chametz one already owns, certainly going to buy more chametz would be wrong, or as the OP puts it it is counterintuitive to the spirit of this commandment.
The Ramma again at the end of siman 445 mentions a minhag where if no chametz is found during the bedika, to burn the item used to do the search so as not to forget the chiyuv to do biur. (I guess this is where the feather and wooden spoon comes from, easily combustible items).
This is a hindsight minhag, but again we don't see anyone saying 'it would have been better to buy some chametz beforehand in order to avoid this. And again, the aforementioned Taz which is taken quite seriously by a nice list of achronim would have been completely ignored in doing so.