In both cases there is a described mechanism which produces the effects that are observed. In the case of Moore's law the mechanism has now been thwarted by physics, everyone knew that this had to happen at some point, but the surprise was how long physics was staved off by clever engineering. In the case of Eroom's law the mechanisms seem strong, regulators will continue to strengthen or at least remain as strong, new drugs will have a higher bar to jump due to old drugs, market economics will dictate that firms will throw money at high risk projects to hail mary out of trouble. So to say that nothing about these trends must hold true misses the point that they are/were strongly founded and could be used to make good predictions about the evolution of the economy and society.