That's one way to put it, Off Kilter.
To answer the question, it's mainly that Haverford has had a lot of all-time great runners. But like Lau, they've overlapped with some other all-timers.
Schilit was not even the fastest guy in D3 the weekend he ran 13:59- Tim Nelson ran 13:57 and ran away from him at nationals like he did in every race that year. And when Schilit went down to 1500, he got beat by Dan Sullivan, who was a 3xnational champ. Marquardt was never able to outmaneuver Paul Escher (another 3xnational champ). We also had Avi Bregman, who was a top-10 all-time steeplechaser the year that Mike Leduc ran 8:45 at nationals. Those guys overlapped with 2 national champions (Hulleberg and Stadler) and a team XC title, so it's not like Haverford completely struck out in that era.
Bottom line, it's hard to win when everyone else is really good too. Just ask Ryan Steinbock.