For a close reason to be displayed, it requires only three of five users to select that reason. It's possible that two of them chose something else, e.g. off topic, since you're asking for a product recommendation. That's actually prohibited, even if not explicitly mentioned on the FAQ.
Regarding the close reason not constructive, and why it applies:
It's not a difficult question. You can get a list of possible benchmarks in two minutes seconds using Google (edited to add: the accepted answer is the second hit for linux system benchmark for me). There's probably even a Wikipedia article on general computer system benchmarks, including those for Linux, so it does not require specific expertise.
So what usually happens on SU is that there will be lots of short answers that have barely any value, and community users will vote on what they like best — i.e. polling.
Since there is very little in the way of requirements (which might have made this an interesting question at least) that would allow matching answers mostly objectively against them, basically anything resembling a benchmark is a valid answer, and all that's left to determine the value of any answer is personal preference — which is where opinion, debate, arguments, [...] or extended discussion come in.
We had the worst of this kind of question in the early days, asking for the most popular freeware/software/open source programs or most hated of those, with difficult answers such as Firefox or VLC media player being at the top (or iTunes for most hated). See this list of anwers upvoted 100+ times for the topic titles.
Regarding that first bullet point: I'm not sure if you're serious there, but assuming you are: A question mark at the end of a sentence does not make it a good fit for the Q&A format of this site. It involves more than just writing a question. Please see the FAQ for what kinds of questions we don't like, including:
[...] avoid asking subjective questions where …
- every answer is equally valid: “What’s your favorite ______?”
- your answer is provided along with the question, and you expect more answers: “I use ______ for ______, what do you use?”
- [...]
Matching those examples against your question is easy. Given that they're just examples, I took some liberties with the format.
What's your favorite Linux system benchmark?
I use Windows Experience Index for benchmarking my system on Windows, what do you use on Linux?
What to do instead
- Search yourself. Seriously. Asking and receiving answers is free, so please show some respect for our time. We'd rather help those who are willing to invest some time in finding answers themselves.
- If step 1 doesn't solve your problem: explain that you searched in the question, without being prompted, and why the results you found (mention them!) don't work for you.
You need to be aware that asking for product recommendations is considered off topic. You might escape the diamond moderators, but there's no guarantee.
