When the Athletic say "some clubs" they mean just Liverpool. They're covering Liverpool's arses.
Thats your take on it. I'm certainly not going to jump to those conclusions, but if a club is using caffeine to help players you will get a short term gain for long term pain.
I remmeber seeing this with boxers as well, they will do all sorts of short term ways to lose weight, but they kill their metabolism in the process (and why many end up chronically overweight). Caffeine is about as bad as you can get for your metabolism, just below sugar really. You'll get this massive high, but eventually your body becomes de-sensitised and drained.
I remember the article from someone (who I believe hasn't been sued by LFC) essentially saying they will have massive problems as they are cycling off the meds. I don't believe the specificities of the article, but he does seem to have called this injury crisis right to a tee. The intensity goes and then injuries start piling up. I really don't think it's going to stop, or that even 5 substitutes is going to do much to help it either.
I don't think people really grasp the damage Klopp did on leaving Dortmund. That final season was a shambles, and an entire team, who were not far off the current Liverpool side in ability became finished (with one or two notable exceptions).