This is what the article basically says: Obama has grown the budget by the smallest amount since Dwight D. Eisenhower. So, the budget is essentially exponential. They start with Reagan, the galactic conservative emperor. He grew it by a pretty astounding rate. No one is going to shrink the budget, so on top of what Reagan did, Bush added more, grew it more. Then Clinton grew it a little bit more. So everyone is growing it and inflation is also growing it... but the reality is that among those that are "doing it" (growing the budget), Obama is doing it the least. He's the least guilty when it comes to contributing to bloated government. BUT the GOP consistently paints him as the worst offender and don't even get me started on the way the Tea Baggers are trying to myth-make with this president.
I think these numbers are important. Their point isn't to measure "economic outlook" or "percentages of GDP." The point is to myth-bust the bullshit about Obama being a socialist, big government spender. He's clearly not.
You really need to read the fact check link. Obama grew it the most, if you assume the rest of the OP's chart is accurate. Comparing the debt to GDP ratio is necessary b/c absolute numbers don't matter when the size of the economy and the value of $1 are constantly changing. Otherwise this would be like saying someone who takes 1 piece of a 10" pie in 2010 is taking less than someone who took 3 pieces of a 100" pie in 1992.