It comes down to what you're boiling for, right?
Extracts don't truly need to be boiled to make wort. Specialty grains have already been converted by the steep. We boil them for ~15 minutes minimum as a precaution to pasteurize it. Palmer talks about wort darkening, foam stability, etc. as being the effects of boils (with respect to boil gravity and time)..I swear to the good lord, if in brewing all I had to worry about was "foam stability," I'd go pro.
as an extract brewer of novice experience, I'm boiling to work my hops. I'm targeting an IBU number that the software spits out, but in reality the hops are doing so much more and I'm scheduling my hop additions based on experience, even though were still targeting a number out of a black box program.
another reason to boil is to cook down your volume to hit a target OG, but this is a mechanical solution to a mechanical problem.
god, I'm rambling (don't post from happy hour at the pub while on your third scotch ale)...point is, there is a lot of art to this craft (which is 1/2 the fun). Adding the lme/dme to cold water before the boil is fine.