Its a trick to use the actual detailed data instead of a general, over-broad, and simplistic view? Interesting. I have seen the graphs that you posted. Many times. But here's the thing. Near the end of the period you cite as being the "best" business move DC could have made, we see something very important: DC's decreasing sales, which is what made Rebirth necessary in the first place. Again, why was Rebirth necessary if the New 52 was doing so well? And again, as pointed out, only about HALF of DC's sales by the time Rebirth rolled around were attributable to their regular titles. Who knows where they would have been if they had just been selling New 52 titles. Probably nowhere near that level.
Also what I see during this period is Marvel taking off significantly. You say that the New 52 basically helped DC reach unprecedented heights? Well, how does that explain Marvel's meteoric rise? It doesn't. What does explain it is that the industry itself was growing.
And furthermore, here is a chart showcasing the marketshares of the top publishers:
So, in a time when the market is apparently on the rise, Marvel and Image appear to be benefitting significantly. Meanwhile, DC by 2015 appears to be in dire straits, with significantly less marketshare than what it had in years preceding the reboot. And again, this is in an era where DC was relying heavily on NON-regular titles to even get its sales up to where they were.
Pair that with the fact that several of the New 52/DCYou titles faced severe drop-offs in sales...
...and yes, there's a problem. One that needed to be addressed.
And that's the thing: DC did address it. Your argument may hold up if the New 52 was still going on, but...its not anymore. DC pulled the plug on it. They have spent the last two years essentially undoing it. So, again, if the New 52 was this gigantic boon to DC Comics, then why did they feel the need to literally rip it to shreds?