User blog comment:Gogogadget831/Character Appreciation - Week 2: Amy/@comment-24152851-20170111071236/@comment-4742462-20170112181850

Because it ends up being their only purpose on the show and once it was resolved they were booted. Similar earlier conflicts (Gwen/Leshawna & Heather, Courtney & Lindsay, Duncan & Harold, etc.) were written so that said conflict wasn't the only purpose for said characters.