Bell did not advance to UIL State Finals in 1998, mainly because of a spread in music scores. One judge had them in 1st, and another judge had them in 21st. The 21st place rank score kept them out of finals.
The rule you are talking about was put in place after the 1998 UIL State Marching Contest. I have heard that it was implemented as a result of what happened to Bell in prelims, but I cannot confirm that as a fact.