Agreed. GearScore actively promoted lootwhoring on items you would never reasonably use, simply because it inflated your score to 'acceptable' numbers. I was in several ICC10 pugs where someone snuck in using caster trinkets on their rogue and other such shenanigans because the raid leader arbitrarily decided ICC10 Normal required ICC25H gear. If it were about optimal clear times, the raid lead wouldn't have just been inviting anyone who had sufficient GS, they would still be checking Armory pages and inspecting ingame. The raid lead was just lazy and inflated the required GearScore because that was 'in' at the time.
GearScore just promoted lazy thinking among pug leads, a pandemic that still affects the game to this day with day-one pugs requiring AOTC and an item level only found in previous-tier Mythic. People still aren't inspected to ensure that item level comes from good gearing, or that they didn't just floor-tank the achievement. That is one aspect r.io helps, as much as pugs sometimes/often abuse the system to block people learning the fights out of Normal pugs (YMMV).