If anyone is the defining artist of the 2010s, it's Adele.
21 and 25 are the two most successful albums of the decade.
I agree with 21 but 25 is like self titled and lemonade, they're here for a few weeks and although they sold a lot have very little time in the spotlight before a male artist comes to steal it.
For someone who doesn't "discuss" Rihanna, you sure run to every thread about her. You probably know more about her than me and yes, she is one of the defining artists of 2010.
Rihanna is very good at selling singles but she's not even close to be the defining artist of a decade, her influence is imo very low compared to how well her singles sell