Many changes were unnecessary

The editors have not merely fixed obvious mistakes. They made so many unnecessary changes that fix no errors and make no improvement to the book.

Yes, the editors didn’t just fix obvious errors. They also fixed errors that weren’t obvious. Consider: In law, in music, in accounting, in sports—in just about every field of human endeavor—errors that an untrained person may not see should be obvious to a person suitably trained. And so it is with editing.
To assume “If I don’t see an error, it’s not there” is a sign of muddy thinking.