Q:

Why does every "good" answer here have to involve somebody saying something to somebody else?

Part of interpersonal relationships is knowing when to say nothing.  Sometimes there is no polite way to say what you want to say.  A recent example is this question How can I politely tell a family who invited me for dinner that I'm still hungry?.
In this case, it was not a one-time experience, but a consistent, established pattern.  The OP, in my opinion, answered the question himself:

..... I decided to eat at home prior to visiting .....

Another example is this question about a noisy eater at work How can I ask an unfamiliar coworker to eat more quietly?.  Again, the OP had the solution in his question

Most of the time, I've just been putting on headphones....

In both cases, the answer buried in the question was far from ideal from the OP's point of view.  So what?  Living with less than ideal solutions is part of interpersonal relationships and better than hurting someone's feelings, possibly for no purpose. 
If you are a guest in someone's house, you follow their rules and customs.  If you don't like it, stay home.  If you have a co-worker with bad table manners, leave it to someone who knows him well to speak to him.
There is no kind or polite way to deal with some problems other than gritting one's teeth and keeping one's mouth shut.
However, advising an OP that what cannot be cured must be endured seems to be against the policy of this site.  (See answer of HDE to Why was another one of my answers deleted?).  
Let's not rule out keeping silent as a valid answer when it may actually be the best answer.  Such an answer should explain why the problem the OP asked about is not one of the battles he should choose to fight.   

A:

This site is interpersonal.stackexchange.com, not ihaveaproblemandwantanysolution.stackexchange.com. There's a definitive difference.

First of all, we are a site for Interpersonal problems and solutions. 
We're not Lifehacks.SE, or Workplace.SE. So, please interpret the answer of HDE as saying that you can't answer a question about adressing the behaviour of a loud co-worker by only saying 'wear headphones', or 'go to HR and have them handle it'. 

Living with less than ideal solutions is part of interpersonal relationships and better than hurting someone's feelings, possibly for no purpose.

If you can write an answer that argues (preferably backed up with how, why and experience) that no matter what or how you tell someone something specific, it will hurt that person to some extent, and they are maybe better off by not addressing it, then feel free to write it down. 
You can leave an answer saying 'this is probably the politest thing you could do' ... but keep in mind, it may backfire in such and such a way.... so, unless you are prepared to take the risk, the headphones you're wearing now are really the best solution if you want to keep things polite'. You can't post answers that tell the OP they're being an ass for wanting to do something or post answers that state 'headphones are a good lifehack solution'. Provide your critique as part of an otherwise legitimate answer. 
Remember: 

It's very, very hard to show that there's no interpersonal solution to an interpersonal problem. 
  It's very, very easy to claim that there isn't and then write a non-IPS answer.

This goes for answers suggesting use headphones/go to HR/take a xanax... If you can reasonably argue that the problem will go away with doing nothing, that's good.

There is no kind or polite way to deal with some problems other than gritting one's teeth and keeping one's mouth shut.

If an OP comes here to ask for an Interpersonal skill to their problem, and you're telling them to 'just suck it up, there's no way you can fix this', that's not an answer. 
We should respect the premise of the question of an OP. The basic premise of a question is 'here's my problem that I'd like to resolve'. Not 'here's my problem, I'd like to ignore it'. 

Even if you might think 'just suck it up', doesn't mean that other people can't offer advice about how to broach the subject as gentle as possible. 

A:

This is a site mainly about how to communicate better. Most people come here in search of advice on how to communicate better with other people. Most questions are phrased in that angle.
Of course other solutions exist. But this isn't the place to tell someone to go to HR, or to fire someone, or to break up. This is a place where people come when they think they can find a social or communicative way of working out a problem, and the answers here (the good ones anyways) are supposed to hit that angle.
To that end, "don't talk to them" is an answer, but very often not very useful in solving the interpersonal issue at hand.
It's also incumbent on the askers to pick their battles, and if they ask here, it is at least implied that they care.

