Mordor was starting an industrial revolution which couldn't have been older than 60 years. Nothing explains the lack of development the previous few millemnia.
What explains the lack of development in ancient Sumer or ancient Rome? Wait a hot minute, because we have no idea and could have no idea if there was a small industrial revolution 10K years before ancient Sumer was a suburb. There would be no way to know if something like actual stainless steel was forged 60K years ago and the technology was lost. This is the problem with the blogger's armchair reasoning.
How many areas are seeing reliable ice layer formation? Stuff at the top (most recent) is melting away, too!
So... if the same thing happened before, Industrialization, co2, eventual collapse after warming, ice records may be unreliable...
But it also took many, many thousands of years for us to get to the industrial revolution. And we did not have magic, we did not outsource stuff to elves and dwarves, we did not have wars with orcs and dragons and other monsters and no extremely powerful transcedental/imortal beings actively involved/shaping the development of history.
And we only overcome feudalism because of the plague and the discovery of the New World -- non of which happened in the LOTR universe.