Of course people might choose to vote Curry because they already voted Jokic as MVP.
As for who’s a better offensive player? I think it’s really hard to say. Their games are so different. Curry gets defended the way he does because he will absolutely destroy you if you don’t, he’s special and possibly the greatest offensive player of all time. But just because Jokic isn’t defended the same, doesn’t mean he’s not also special. Jokic would destroy teams if they tried to triple team him... with his size and passing vision, he’d just pick them apart and get lay-ups for all his teammates
So you’ve got 26 points on .64 TS% and 9 assists a game vs 31 points on .66 TS and 6 assists a game.
The box score advanced stats say Jokic has done more... the plus minus ones say Curry is more important. I think it’s close this year.