Evolutionists argue that, in general, homologous (similar) structures or genes are evidence of common (joint) ancestry between the species. They also argue that vestigial (useless) features show common ancestry between the species and a similar species in which they are functional.
Critics of evolution can equally well argue that, in general, heterologous (dissimilar) structures or genes are evidence of disjoint ancestry between the species. They can also argue either that alleged vestigial features are in fact useful or that our lack of knowledge about their utility does not make them useless.
These two groups could go back and forth ad nauseum, or they could call an armistice and accept that in some cases one of them is right and in other cases the other is right. What would biology look like in that case? Biology would admit a dual explanatory regime.
What would this dual biology look like? It would look like a common classification problem to determine for each pair of objects whether they are in the same class or in different classes. The answer is not: all objects are in the same class. Nor is it: each object is in a different class. The correct classification is somewhere in between.
Why is this so difficult for biologists? Perhaps because there are so many organic species that a simplistic answer to their relationship is better than no answer. But in that case it would be best to have both groups compete for the best answer. Don’t give a monopoly to one group (i.e., the evolutionists) but encourage their critics to give a better answer. Ironically, that’s close to where biology was before evolutionists took over.
Unfortunately, the academic world doesn’t do well with competition. So academic science tends toward monopolistic science. The competition takes place outside the academy, in independent research institutes. That’s where the cutting edge of biology is.