It's a general consensus that is based on absolutely no empircal data whatsoever. I posted a while back asking if anyone had ever encountered any real evidence that there was any difference in build quality, and absolutely nothing came forward. No one who had ever compared two identical models made in different countires and observed a difference, no one who knew of any statistics from anywhere showing that non-Finland models were returned for repair any more frequently, nothing.
Instead, I got a lot of responses along the lines of the following:
Utterly baseless, unsupported conjecture. Not an iota of solid evidence showing that anyone on Earth has ever even encountered anything suggesting a difference in build quality related to country of origin. Just a lot of facile speculation and simplistic rationale to perpetuate a rumour that never should have gained any traction but somehow did.