This is in part a duplicate of Suggested tag: keep it short and simple. Regarding other points, I can only agree with your assessment that the quality of answers to that question is somewhat lacking, and that it might be down to the question being fairly basic, with perhaps still the best answer in the first paragraph to Wikipedia on Escape velocity, which should be easy enough to find, if our requirement for prior research before posting questions was met in this case.
I tried to prevent a flood of less than helpful answers and OP changing the meaning of the question by protecting it (anyone wanting to answer it would first have to gain 10 reputation points on our website, which is a rather mild restriction) and reverting the question itself to the revision it received multiple answers to, but as you can see in other comments (some by now deleted due to "too chatty" and/or "rude or offensive" flags), even that was disputed by hit & run visitors to our site with no prior positive participation, and in the lowest of forms - calling names because some new members apparently thought some others they follow and that couldn't post an answer can walk on water, or something like that.
Why has this happened? Because the question hit what we refer to as the Stack Exchange SuperCollider. This exposed the question to far greater Stack Exchange-wide visibility than normal, and all the qualitative aspects we work on hard on our site fell into the deep end of the popularity vote pool. And of course, there's always attentions seeking Stack Exchange members that find it beneath them to answer a question that might be less popular or harder to answer, and will get intimidated by any form of restrictions imposed on them, regardless how trivial they are to overcome. I'm not saying some answers posted there are not helpful. They are, but you'll find far greater quality and less needless reiteration of much the same points in most other questions.
What can we do to prevent this? Not much. As a 2.5k and counting member site, we're with such questions at the mercy of far more numerous communities with their member count in the hundreds of thousands. We can guide by example, and work on improving the quality of all aspects of our site, questions notwithstanding. Don't let it bring you down (ignore, if that helps) and demand quality and specificity regardless of the number of prior votes posts in such threads might have received. I.e. don't submit to the lowest common denominator. Expect quality when you vote, and try to match or improve it with your own contributions. And when you deem some sort of action is required, vote to close with a suitable reason, or flag to bring it to the attention of moderators. If things get heated up, and you require faster response or merely want to talk about it with our more active and experienced members, then I'd suggest stopping by in our main chat room.
