In a word, no.
If the answer is not a good one, it should be downvoted. Questions can be on- or off-topic for the site, but ultimately as long as an answer addresses the question, it shouldn't be removed or disallowed. This site focuses on Raspberry Pi usage, but it wouldn't be constructive if we artificially enforced pigeon-holing solutions.
A good answer of this kind should likely be accompanied by a recommendation for an alternative. As with all answers, a one-line response is not a good answer. A good answer along these lines will have some explanation.
In addition, "the Raspberry Pi isn't suitable" may be correct, and sometimes it may even be the best answer, but perhaps the accepted answer will be a way of achieving the task using the Raspberry Pi, even if using this device isn't optimal.