Late LME addition

What is the reason for splitting a LME addition and saving one to add at flameout? I think I readget about it before on a posting or Palmer's book, but wasn't able to answer the question

Hey GoodisBeer,

There are several reasons that I can think of.  1) To increase the hop utilization, a lower gravity wort means better hop utilization.  2) Lighter beer color.  With a high gravity wort, the sugars are more likely to caramelize or scorch producing a darker beer.  3) Less caramelized flavor allowing the yeast, grains... to come through better.

I have switched over to DME for the reasons noted above and my beer quality went through the roof.  Even with DME, I still do a late addition.

There are some that will disagree with me that DME produces light color and lighter flavor beer, however my side by side comparison shows me otherwise.

See for your self
Toy4Rick

Does the extract still need boil time? I have read that it ought to be to ensure that there isn't anything undesirable riding with it. What are the odds?

From my reading and experience I say "no".

The wort has already been boiled and then turned into either LME or DME for you.

Throwing it into boiling water late and just boiling for a few minutes, or even at flameout is still subjecting it to 200+ degree temps which should kill anything that you may have added to it while handling it.