It means, that mt-MRCA must be not 200 000 years old, but under 10 000 years old.
I don't even think you have to understand genetics (etc.) to figure out that our most recent common ancestor must have lived quite recently. Simple math will do - we have 2 parents, 4 grandparents...2^(n+1) n-grandparents...if you go back more than about 30 generations the number of our direct ancestors becomes greater than the population of the earth at that time. Of course you have to allow for liaisons between close relatives which were probably more the norm rather than the exception in times past, but even so, I doubt that could stretch the lineage from our MRCAs to more than a few thousand to perhaps tens of thousands of years - I don't believe it could be hundreds of thousands of years back...
...but so what? That MRCA of ours, was part of a huge population which also had its own MRCA thousands of years before that, and that MRCA of theirs was part of a population that had its own MRCA even more thousands of years before that...etc...
...so, so what?
I suspect perhaps one of the very much more ancient common ancestors of all humans was, in fact, a fish: