After all these years, perhaps its time to re-examine the assumptions.
it's always fun and useful to re-example assumptions. for example, anyone who assumes that because the attacks they happen to see, or the attacks they hear about lately, don't use spoofed source addresses -- that spoofing is no longer a problem, needs to re-examine that assumption. for one thing, spoofed sources could be occurring outside local viewing. for another thing, spoofed sources could be "plan B" when other attacks aren't effective. the last thing is, this is war. information warfare. the enemy knows us better than we know them, and their cost of failure is drastically lower than our cost of failure. don't be lulled into some kind of false sense of security by the fact that YOU are not seeing spoofed packets TODAY. let's close the doors we CAN close, and give attackers fewer options.