I’ve never seen anyone talk about it much, but when you think about mass extinctions, you also have to think about rates of change
You can think of a species occupying a point in a many-dimensional space, where each dimension represents some parameter that influences survival and/or reproduction: temperature, insolation, nutrient concentrations, oxygen partial pressure, toxin levels, yada yada yada. That point lies within a zone of habitability – the set of environmental conditions that the species can survive. Mass extinction occurs when environmental changes are so large that many species are outside their comfort zone.
The key point is that, with gradual change, species adapt. In just a few generations, you can see significant heritable responses to a new environment. Frogs have evolved much greater tolerance of acidification in 40 years (about 15 generations). Some plants in California have evolved much greater tolerance of copper in just 70 years.
As this happens, the boundaries of the comfort zone move. Extinctions occur when the rate of environmental change is greater than the rate of adaptation, or when the amount of environmental change exceeds the limit of feasible adaptation. There are such limits: bar-headed geese fly over Mt. Everest, where the oxygen partial pressure is about a third of that at sea level, but I’m pretty sure that no bird could survive on the Moon.
What this means is that, when considering environmental changes that are within the limits of adaptation, rapid changes are much more likely to cause a mass extinction than slow changes. An asteroid strike (of sufficient megatonnage) is far more likely to cause a mass extinction than changes in sea level. I’m not saying that an asteroid is the only way to cause a mass extinction: I’m saying that an abrupt event is far more effective than a slow change of the same magnitude. For creatures with short generations, like insects, even 1000 years looks slow.
Several orders of insects disappeared in the Permo-Triassic extinction, the biggest of all. Whatever caused that extinction must have been a humdinger.
Paleontologists prefer gradualist explanations for mass extinctions, but they must be wrong, for the most part.