Well success isn't opinion based, we can see and use numbers so objectively speaking and not bringing up feelings or arbitrary and non quantifiable entities like 'impact' or 'hype' than yes. Twice have also. Numbers pretty much across the board confirm this. When you reach the top of the pile over the last 2-4 years it's expected as you're getting a slice of a much much larger pie than SNSD, Kara and 2NE1 had say 5-8 years prior.
Kpop is globally bigger now and those groups simply sell more, have higher sps and global music sales from. They also tour currently better than SNSD did in their prime in terms of venue sizes and would have put much much bigger numbers on the board if a pandemic didn't steal 2 of their prime years from them.
It's in ways an unfair comparison as, again, success isn't an opinion it's a fact expressed as a number in the relevant metrics and that shows BlackPink are more successful. The unfairness is that the market for Kpop now is simply a lot bigger in almost everyway so it's expected for modern groups to do better than their historic competition.
If you're talking about cultural saturation, domestic fame and sales, etc thats up for debate and a much different question, but if you're talking pure success than that's not.