People upvote answers because they are clever, witty and entertaining, even if they are clearly outside the scope of Worldbuilding. Worldbuilding is generally about coming up with fictional worlds which if not realistic are at least plausible.
In the linked question, accelerating a single proton to sufficient energies to disintegrate a planet is completely implausible and integrating it into a fictional work would require some serious handwavium, considering the most energetic particle ever detected, 10 million times more energetic than anything we can create with our most advanced accelerators, hit with the energy of a baseball travelling at 55mph.
The energies involved in that answer at least would only take about 1 week output of a dyson sphere, magnitudes less energy, than say steering a neutron star into the Earth.
What these answers have in common, is they are clever and entertaining, they answer the title of the question, and basically disregard the text of the question. For example in the linked question, even in the original version of the question it specified "chemical element, get out your periodic table" (last time I checked, Neutron Star is not on the periodic table), and that this was to be done by a "mad scientist", not a wizard or a civilization with extreme hypertechnology. Neither of the top voted answers are answers even to the original question - let alone the revised versions.
I think one of the things people like about Worldbuilding is that making stuff up is generally permissible. If someone asks a question on Space which is too speculative (i.e. cannot be given a scientifically sound answer), they might be told to ask it on Worldbuilding instead, because on Worldbuilding speculation is welcome and answers don't have to be scientifically sound. It is a site where people can have fun, and maybe it becomes about having fun, but this could easily degrade the usefulness of the site if poor answers are consistently upvoted (yes, I'm sure some people ask questions in the hope of getting entertaining answers, but I'd hope some people ask questions because they are making a fictional world, for a novel, game or so on).
Answers should actually attempt to answer the question as a whole - not merely answering the title taken completely out of context. Furthermore, plausibility in general should be valued, unless the question indicates that it is a fantasy world with high magic or hypertech.