The article is probably right about the bare facts, but it seems much like one of those that insist that Y2K was a big nothing, and that the Population Bomb fizzled.
In each case, there was a warning that was followed by a phenomenal amount of hard work in back rooms to head off disaster. Disaster was headed off successfully, and then the people who had warned about it were criticized for their failed prediction. In the case of population, we were very, very lucky that the Green Revolution turned out to be possible. There was no reason, beforehand, to expect such an idea to work well enough. (The Green Revolution, with its dependence on fossil-fueled fertilization, has ironically contributed to the present crisis.)
Would CO2 emissions have continued on one of the higher curves, without enormous investment in solar and wind power systems, and in more efficient usage? Counterfactuals are hard to prove, but I don't see any reason to think not.
What I notice about the graph is how lines below current and projected emissions, that identify behavior needed to prevent readily predictable disaster, are omitted.
That current climate research must compare improved methods using the same reference numbers that previous papers used, despite those numbers being now obsolete, seems like a small problem compared to others faced in that field, such as the still unpredictable behavior of cloud cover in different scenarios, or of ocean currents.