One disadvantage of Internet correspondences is that you do not get to hear/understand the intonation of someone else's sentences. For example, suppose that I told you, "You were damn wrong to say ...

I think the answer is simple: Because people want to earn reputation points, and possibly even a nice golden badge, or at least a silver. A nice strategy in this context is to answer this kind of very ...

$\overset{\mbox{This?}}{\longrightarrow}$ $\overset{\mbox{This?}}{\longrightarrow}$

Apparently, the expression inside the "tag" is interpreted as a text, not a math formula. Try this: $$a^n + b^n = x^n \tag{F$\Phi$}$$ which yields $$a^n + b^n = x^n \tag{F$\Phi$}$$