And of those, only Dembele was a teenager when they signed him, and one with a full season of Ligue 1 football at that. Aubameyang was 24!
Dortmund's transfer policiy really is overhyped, the only players that really fit the mold of it are Sancho and Bellingham(even he's a stretch with it, he also had a full season under his belt), all the rest are typical big club signings, just plucking the best players from smaller teams.
I'm convinced Dortmund aren't actually interested in Chukwuemeka, it's just an easy and lazy link for the media, I believed the Leipzig one last summer much more because it wasn't as obvious.