You seem to have missed the point of Booth’s article
I pointed out that the report exaggerated because many of the drugs appear in multiple indications and multiple trials - cancer is not one disease. If you actually look at the PHRMA report in some indication, you will see that there is actually not a lot of overlap between similar drugs in the same indication. So I do understand the concept of multiple drugs chasing the same target.
I have no idea if the 1,400 trials in RA is because of a few drugs being used in multiple trials or if it's because there are many new drugs being tried. Do you?