In my mind Meltdown is a failure of implementation due to the choice to violate the logical design. If the logic of your design says "do not access ringX memor

In my mind Meltdown is a failure of implementation due to the choice to violate the logical design. If the logic of your design says "do not access ringX memory if you are not executing in ringX" then don't do it. Intel instead decided that they would access it but thought they could hide the results of that access from the process by never providing the read results. The problem is that actions always leave evidence in the physical world, simply assuming that no one could detect those actions (which was true at the time) is not the same as not committing the action. The benefit for Intel in violating the logical design rule was speed (and probably a reduction in gates) and the optimistic view that there were no consequences to the violation. Unfortunately hubris invited Nemesis to the party, as usual. Spectre is a different problem in that the very design of speculative execution contains the seeds of its flaws so there really is no way to implement it in such a way as to avoid the intra-process snooping although the inter-process exploit may be avoidable via implementation.