Going way back before Shuttle, weren't Gates 78 and 79 used for United Express flights? It seems to me I remember boarding WestAir Bandits by walking down the stairs at 78. And I also recall boarding a WestAir UAX BAE-146 at 79. So, Shuttle did not originate those stairs.
That was all before UAX was relegated to a remote terminal at SFO.
"Travel is fatal to prejudice, bigotry, and narrow-mindedness." - Mark Twain