This all seems a bit off the point to me.
Firstly, language needs sometimes to include words to describe offensive behavior.
Mansplaining seems to me to just mean patronising and boorish behavior by a man towards a woman.
It's just shorter and more concise than actually saying all that.
I don't get the jump some posters have done from that word being in existence, to the fact of it's existence meaning that all men are patronising boors.
The word mysogyny exists, meaning to hate and fear women. The fact that it exists does not mean that anyone thinks that all men hate and fear women.
The existence, and occasional use by women on this forum of that word, does not generalise at all. It specificates.
Meaning it is describing a specific incident or behaviour.
And I agree with Coley's metaphor about "whitesplaining"
If I am white, why would the existence of that word apply neccessarily to me?
The fact of it's existence would simply mean that one section of society has recognised a certain behaviour from a different section of society.