In our HS, freshmen are offered the opportunity to take AP Seminar based on their PSAT 8/9 scores. The class, however, is purely an elective (it doesn’t even count towards an English requirement), Our HS is heavy on requried classes (four years of gym, plus consumers ed, drivers ed, a fine arts class, etc.) and stingy on the elective spots, especially to students wanting/needing to get four years in of each core requirement.
So while I believe the research skills taught in the class would be useful, as a practical matter, any STEM hopefuls plus anyone in band or chorus (folks who’ve by default used up a precious elective spot) tend to take a pass on it. There just isn’t enough time.
It might be and attractive and worthwhile choice for a humanities hopeful, though. I’ve heard some high schools will count it in lieu of a required English class. That would change the equation too.
Honestly, unless you’re looking at it as the humanities version of PLTW, I am not entirely sold on the idea that it “adds a competitive edge to a college application”. At least not in our high school where most of the best and “high performing” students don’t take it, even after the school plays it up by sending them a special invitation to do so.