theres a good explanation for that actually
lets say you’re a pro working yourself up from nothing. you notice all these tier 4 teams that consist of
4 riflers (1 igl)
1 awper and sometimes 2ndary awper
the odds of you getting a team if you’re a rifler is much higher. not just that, but an awper obviously needs to be great with rifles too so everyone is a rifler to begin with (except bot jdm).
so i would assume most awpers way back then became awpers out of necessity, when a team needed an awper. they have since trained themselves primarily to use the sniper instead.