It's possible we didn't even hear of this person yet? Who heard of Obama in 2002?
This got me curious, what were future nominees up to 6 years beforehand
2020-->2014: Vice President Joe Biden / Businessman Donald Trump
2016-->2010: Secretary of State Hillary Clinton / Businessman Donald Trump
2012-->2006: US Senator Barack Obama / Governor Mitt Romney
2008-->2002: State Senator Barack Obama / Senator John McCain
2004-->1998: Senator John Kerry / Governor George W. Bush
2000-->1994: Vice President Al Gore / Gubernatorial nominee/son of ex-President, George W. Bush
1996-->1990: Governor Bill Clinton / Senator Bob Dole
1992-->1986: Governor Bill Clinton / Vice President George H. W. Bush
So it seems for the most part that future nominees are nationally-known figures 6 years out from the election, with the notable exception of Barack Obama in 2008. Even Trump, who nobody would have predicted as the Republican nominee in 2010 or even 2014, was still a household name.
So it would seem that Obama is the exception to the rule.
1970-1976: Fmr. State Senator Jimmy Carter / Representative Gerald Ford...just saying
