Why is check a rule?

I've never understood why check is an actual rule. As a pure term I can understand it, but why should it be illegal to perform a certain move?

I should have the option of moving my king into check. And my opponent should then have the option not to take it. As it stands it's just a lollipop rule to prevent beginners from making mistakes. Why shouldn't they be allowed to make mistakes?

If moving into check is illegal, why is it legal to promote to a rook or bishop? It's clearly worse than promoting to a queen, so let's ban it. Beginners could get sad otherwise.

Ah, yes, the King-sacrifice would be even more glorious than the celebrated Queen-sac!

Sometimes promoting to a queen can result in a stalemate, whereas underpromotion can avoid stalemate.

Yeah, instead of a king sac, you could just resign the game.

If you could move into check there would be no checkmate

You just don't question these things. It does no good.

I tend to agree with the OP... If you hang a rook, a minor piece or a queen then it can get taken, and often times it will lead to you losing the game. Yet if you "hang" you King, which should be much more serious than hanging any other piece, nothing happens, and you just have to make a different move.

total nonsense...

Why is it legal to produce stalemate then? Clearly that's bad for the player that is doing it, so it should be banned as well.

If stalemate doesn't exist, and check (and by extension, checkmate) doesn't exist, how does the game end?

Start your own Bontrager Chess variant, see who follows.

(Methinks there's a chance I'm being trolled; Either that, or I'm talking to a 3-year old. (Why? Why? Why?))

So, you mean if you hang your King is an automatic loss. Cause the point of the game is to checkmate the King.

Underpromotion is sometimes the best strategy.  There was a recent game where Nakamura promoted to a knight to win an otherwise unwinnable game.  Underpromotion is not necessarily a mistake.

It is a loss only if your opponent sees it and captures your King. Which is how it works in OTB blitz games.

Answer my new question instead: why is stalemate allowed? By the same logic as moving into check is banned, producing stalemate should be banned as well. It is always bad to produce stalemate.

Me and my friend are having a lot of fun playing without check. Sometimes he moves his king into mine and I don't take because its funny.

Moving into check isn't banned because it's bad. It's banned because people want chess games to end with one side having absolutely no way to prevent his King from being captured (aka "checkmate"), rather than ending when one side accidentally allows his King to be captured when he could have avoided it.

Ah, so you DID start a Bontrager chess variant. Excellent!

So what you're saying is to hypothetically make stalemate "illegal"? Then I can think of a good example where this would be horrible:

Anyways, sometimes I see pro matches where they move like:

1. Nf3 1... Nf6 2. Ng1 2... Ng8

And then they start over again. Maybe they are having a little bit of fun too or what is the purpose of that?

I think they might be trying to remember how the horsey moves...

(But seriously, I've never seen this. Can you provide example games?)

Warming up those finger muscles