The reason why this battle is called a "meat grinder" is that the huge number of casualties on both sides in this battle only reflects one aspect of the "meat grinder".

Another aspect (and a more important aspect) is that this word fully reflects the nature of this war (World War I)!

In layman's terms, the nature of World War I was a dog-eat-dog war between the established European powers. Both sides of the war were unjust.

Therefore, in one of its battles, if both sides suffered heavy casualties, it would not be excessive to use a derogatory or ironic word to describe it.

But the other battles listed by the poster are different, such as the Battle of Leningrad, the Battle of Stalingrad, the Battle of Kursk, etc. They all took place during World War II.

The nature of World War II was a war between fascists and anti-fascists. There was a difference between the just side and the unjust side in this war.

So it is not appropriate for you to use words like "meat grinder" to describe one of its battles.