Actually, there is a grain of truth in this, pandemics are obviously most lethal to more vulnerable populations. Before modern medicine the more healthy and genetically fit survived. Those that survived had, in general, longer lives and those genes were passed down to future generations creating demographics that were more resilient.
This played out during the bubonic plague (Dewitte, 2014) and on a catastrophic scale with small pox in the Americas.
Fortunately, with modern medicine we do not have to go through such turmoil just to have future generations survive and prosper.
As for forest fire suppression, the analogy makes some sense because through fire suppresion it has completely changed the environment that those species live in, allowing certain less resilient species to colonize and allowing other populations to take on traits less suitable to surviving the natural fire cycle that should have been occuring. This creates the opportunity for when fires that do occur to become even more destructive due to more plant material present and less resilient populations. That is why management strategies now have shifted to control burns to allow a more natural fire cycle to reduce material, help sustain native populations that are resilient, and also ensure less damage to infrastructure from uncontrollable fires.