It's such another of many commercial holidays, that I don't particularly care one way or the other. Parents who are worth honoring (because not all parents are) should be honored always and not just one day a year. For those parents pulling double duty - I never saw it that way. You're a parent, so parent, there is no split duty when a child has both parents in their life, at least there should not be -it's a shared thing. Now, extended family members who have had to step up because both the kid's parents are not in the picture - that to me is amazing. I have a few in my family, and I feel they're completely under appreciated/underrated.
"Injustice Anywhere Is A Threat To Justice Everywhere." ~ MLK