You're describing social impairments, which are there too, but this is a different issue. More common with people that have very severe ADHD symptoms, moreso than ASD ones.
What causes the "ADHD as extreme follower" issue -- which I have speculatively explained as a concequence of repeated social rejection with the capacity and desire for acceptance.
This is quite different than in actual BPD where I'm not even really sure BPD people actually understand social acceptance or really want it. It's more extreme than that: there isnt a basic capacity for identity developed enough to actually have a BPD person understand that they are or are not accepted. Not least, since most BPD are actually readily accepted into most social groups over the short term. Whereas in ADHD, impulsive responses impair that acceptance over most time horizons.
ADHD frequently involves Rejection Sensitivity Dysmorphia, which makes someone more attuned to, while also more likely to misconstrue, social signals.