This is nothing new, TOC people have been advocating this for a very long time as part of their "5 focusing steps". But if it is why don't we do it?
Well, because it is hard work. To identify the bottleneck you can't just sit around a table and have a meeting with the managers to define what is the bottleneck. You have to go to the Gemba and analyze the process "as is", not as "it should be" and make some actual work on data collection and analysis.
Once you have done that you are then equipped to start searching for the bottleneck, it's location is buried in the data and process map you just collected.
To find the bottleneck you have to work hard, but finding it is just the first step! Much more is to come...