Because some of those who have asked this question are not just:
1) "cheap", to use the US term, "tight" or "mean" to use UK English, or,
2) genuinely short of funds, or,
3) suggesting scenarios which scream "fraud", or "scam".
Anyone who seriously thinks that a computer without battery, install disks or box is a good buy irrespective of price unless you want spare parts - or, even, perhaps a legit buy - needs their head examined. They are either naive or blind. Or complicit. This is not a good buy, rather, it is throwing money away. That is why MR members suggest that if you are seriously contemplating spending the guts of $500 on something so self-evidently flawed, why not have peace of mind, a proper computer, and a legit transaction for a mere $ 200 more?