Red Velvet was more successful than f(x) for two reasons. Because they weren't active at the same time as SNSD and they debuted in 3rd gen instead of 2nd. Despite these handicaps f(x) was extremely successful and considered a legendary group for their uniqueness and discography.
But what if we rotated f(x) and Red Velvet? What if f(x) debuted in 2014 with the full support and focus of SM as their primary girl group? Could we have seen a more even playfield between Blackpink, Twice, and f(x)?
Reasons why f(x) would give Blackpink problems:
SM is still the biggest company in kpop and 100% devotion to a girl group like f(x) would make them a huge opponent.
In order to compete with BP you need a huge following in the west and f(x) would have been way more popular in that regard than RV.
Krystal would be a great rival to Jennie as it girl. She is only one year older than Jennie so they would be debuting at the same age basically.
Amber would be much more accepted and popular during 3rd gen.
f(x) was top 3 girl group in China during 2nd gen and would probably be the same in 3rd. Victoria and Krystal was a big part of that.
Having Luna on your roster will always save you from live singing scandals which increasingly became a favorite topic of k netz.
Sulli vs Jisoo battles for most beautiful kpop idol.
Or would none of this matter as YG groups just appeal more to the west because of their roots in hip hop while SM is more experimental?