It sounds like those performers would have left you wanting more, even if they had a terrific backing band. The performance is what failed you, and not their choice of media. There are many fine singers who entertain with tracks, and if the show is well executed, and performed with humility, and style ... the crowd will love it. I don't think the set-up lowered the bar for you ... it was the lackluster performance of the entertainers. The same thing could happen with a sub par OMB ... even with great gear. Using an arranger is not a step "up" from using tracks. It's a creative choice, and the right performer can captivate an audience with almost anything. The tools are just a means to an end.