The point that knowing how to do something is not the same as knowing how something works is a good point, and it is true that knowing how to do the tables does not equal knowing deco theory. But it puts you a lot farther in that direction than just knowing how to operate the menus on a dive computer.
When I first started diving, PADI tables were still based on the US Navy tables and they included all the times and depths to 130 ft including deco profiles that did not require a stop deeper than 10 ft - for "unintentional" decompression purposes.
A fairly close inspection of the front side of the tables made the point that in the event of a watch or depth gauge failure, or an unintended delay on the bottom where you exceeded the NDL's but did not remember the deco required, a 5 minute "safety" stop would cover the deco required for fairly substantial violations of the NDL's and 7 minutes covered almost all of the reasonable single tank scenarios. Knowing that provided the basis for a fairly solid contingency plan for the era in the event you were unsure of depth, time, etc.
At the same time, I also understood my SAC and the tables well enough to know that on the first dive of the day to depths shallower than 100 ft, I was gas limited and could not exceed the NDL's. Again, that provided contingency options as well as what amounted to a rudimentary multi-level capability.
Or...to put it in really simple terms, that table knowledge allowed me to develop very simple contingency plans that could survive even the most severe human "computer" failures.
I would not have gotten any of that knowledge had I learned to dive a couple years later with, for example, an imaginary instructor or agency who decided that all students needed to know was how to use an Orca Edge.
