Anyway, by means of illustration I wanted to sketch out how silly it would be for evolutionary biologists to do what macroeconomists do. Imagine these schools of thought:
The Foodians: The Foodians strongly maintain that evolution is primarily driven by access to food sources. When climate changes, the kinds of food growing in an area changes and organisms who are best suited to survive eating the new collection of food available are the ones that survive and propagate successfully. Food drives evolution.
The Climatists: The climatists regularly accuse the Foodians of ignoring underlying causes (despite regular references in Foodian articles to things like changing climates). Climatists argue that it's wrong to say that food supply drives evolution - ultimately changes in the climate cause evolution. Organisms that are more prepared to survive in colder weather, or wetter climates, or what have you are going to survive and propagate successfully. Climate drives evolution.
The Dispersionists: The Dispersionists, on the other hand, think that both the Foodians and the Climatists are barking up the wrong tree. Evolution depends on the availability of lots of genetic variation in a population and this is going to depend on how dispersed or concentrated, large or small the population of a species is. If there are just a bunch of small colonies of an organism scattered widely across the planet with little contact between each other, genetic variation is not going to be as wide as if a lot of organisms of the same species congregated together and could easily travel through the population and mate with each other. Population dispersion is what drives evolution. Moreover, the other schools have a fatal flaw: they consider population variation to be homogeneous! They aggregate too much! Despite the regular mention of variations in the preparedness of organisms to eat certain foods or deal with certain climates, the Dispersionists still accuse Foodians and Climatists of genetic aggregationism... no one quite understands why they accuse them of this. Presumably its because Dispersionists are smitten with the way they talk about genetic disaggregation and like to feel special.
The Asteroidists: The Asteroidists argue that the biggest episode that life has to deal with on a planet is surviving being hit by an asteroid or other incoming rock. Large rocks flying into Earth drive evolution because the impact is so violent and the resulting climatic changes are so all-encompassing that only organisms designed to deal with the extreme cold after the impact blocks out the sun, or those who can burrow deep underground, or even those who are simply lucky enough not to live directly in the impact zone can survive. Impact events drive evolution.
Can you imagine how goofy that would be? The disagreements I outlined above are largely based on caricatures of the other positions. There's very little that is obviously mutually exclusive in any of this, and whatever is mutually exclusive can be explained by acknowledging "yes, X is a process that operates sometimes and excludes the prospect of Y process occuring, but at other times Y may occur without X occuring".
The reason why economists do this is probably mostly because of politics and ideology, but it's allowed to perpetuate itself because we also have a very weak commitment to the idea that (1.) we are scientists - primatologists, in fact, and (2.) we are studying a complex phenomenon that involves multiple simultaneously operating processes.
I think it would be legitimate to say "I study this particular extinction episode a lot, which was caused by an asteroid strike so I emphasize the role of asteroids in my own research but I recognize all the other forces". That's fine. It is also legitimate to have a preference for what explains a large portion of the subject at hand in general, without thinking of other forces as illegitimate or mutually exclusive. What's wrong is to pretend that what we're dealing with should be treated as warring schools of thought. This isn't to say there can never be warring schools of thought. I'm not sure what a good example in biology would be - punctuated equilibrium vs. gradualism? That seems like it might fit the bill. But they should not be as common as they are in economics.