There can only be one THE top group at the same time, by definition. So either the top group was switching every year and it wasnt consistent or there was very limited amount of top groups. Looking at stats and what people are saying, there were a lot of competitors for the top group in 2nd gen, so it wasnt very clear who was THE top one.
Theres really no need to look for agendas where they dont exist.
There was never a clear winner bcoz bb and tvxq , out toured any other group from their gen ( touring >>> ).
2010 Miss A had biggest hit. Bb had best digitals too. 2011 belonged to beast/Highlight with 2 massive hits and good sales. And won rightfully MMA artist of year. 2012 belonged to BB and sistar. Suzy alone overshadowed whole Kpop and any IT girl. Psy rocked that year.
Unless someone topped all three at same time, there was no particular group at top year after year
And cultural impact is subjective term. For artist touring, sales matter.