i just realize that 4th gen have so many popular girl group that everyone is competing with each other on chart and album sales, to the point the ranking will always changing from time to time
for 3rd gen, we only have 5 top girl group (twice, bp, rv, mamamoo and gfriend) .. i would consider Oh My Girl and IOI as a top gg too but OMG peaked kinda late when 4th gen girl group already dominating while IOI only there for 9 months... group like Momoland also have their moment but only for 1 year... so basically the competition is less intense back then.. why do you think the competition on 3rd gen is less intense compared to now ?