Everyone have questions and most of them may be stupid but we must encourage them right? Even some of Newton's questions were pointless.So the negative votes may cause the curious minds to be unhappy and feel that they are dumb. So why should a question have negative vote in StackExchange?
Downvotes send a very clear message: this is not the kind of post we want on the site. (If downvotes outnumber upvotes that suggests the opinion is not that of one grumpy curmudgeon but is perhaps a consensus; if not then the user comes out ahead.)
For answers that means posts that are wrong, muddled, head off on a tangent unrelated to the questions or are just difficult to read and understand.
For questions that means things that are not physics, that presume off-the-mainstream theories, that ask us to do someone's homework, that constitute the eleventy first duplicate of something that everybody asks (search first, seriously) or that demonstrate that the asker would rather we spend our time typing than they spend theirs reading, say, the wikipedia.
We certainly don't have some obligation to answer—or even welcome—every question. Sorry, but that's the truth: this site isn't answerable to every vaguely curious person on the internet. It's like the tour says: "Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics and astronomy." It doesn't say anything about being for every internet user who has heard something about gravitational waves being observed; suddenly noticed that time dilation is weird; or read some book by a pop-sci celebrity.
None the less the site is actually pretty welcoming to rank beginners if they take the time to understand how things are done here. If they learn to frame those basic questions in terms of concepts rather than problems and to focus on the part of the Wikipedia article they're tripping on with an awareness of what other paragraphs say. In other words, if they starting learning to ask questions like a physicist.