I thought it a bit strange that an alternative theory is sidelined completely from mainstream scientific research for the exact kind of lack of evidence that the incumbent mechanism has. No effort to Differentially tally "circumstantial" evidence between what could be a large number of plausible mechanisms and accompanying theories is ever encouraged in a scientific context. When I specifically studied the philosophy behind parsimony and Ockhams razor I came across a descriptive phrase "parsimony would usually imply a shift in the burden of proof". This described precisely what I perceived was happening in many questions between incumbent abiogenesis, evolution, astrobiology, and even astronomical object origins and any alternatives; many of which had some circumstantial evidence in their favour.
These incumbent ideas implicitly become "new axioms" ie. They are treated as "obviously true" and quite crucially are used to come to conclusions critically dependent on these ideas. Remembering that these axioms have no evidence (any more than other ideas that are rejected) the result is that conclusions become "science" equal to that science that is constantly tested through repeatable observable phenomena.
This has been my basis of rejecting Ockhams razor, particularly for the historical sciences, which are not as subject to constant repeatable observable phenomena.
Of course, it is not as simple as that and it has been pointed out to me that Ockhams razor is functional. Without it, one cannot reasonably perform science or engineering. Surely, if a theory is falsifiable, false theories will reveal themselves, and we can, for a time, use any plausible theory as a basis for knowledge in a field until the very moment it can be falsified. The problem to me, is that there is a great discrepancy between aspects of science that are verifiable and aspects that aren't. Aspects that are verifiable deserve no doubt to their validity. The probability that they may be completely wrong is negligible to nil. For aspects of science that are not verifiable, these are determined by a number of different philosophical techniques that may be called a great number of things - syntheses, choosing the simplest explanation that fits the data, generalising a principle from convincing anecdotes, consensus of the peer of scientists who have most deeply studied the subject, etc. the truth is, one way or another, they all amount to Ockhams razor, and they all implicitly shift the burden of proof away from the chosen theory where all other plausible theories cannot be verified including the chosen one. The probability that the chosen theory can be completely wrong, or even impossible, is not calculable by the very nature of the phenomenon that it is explaining, but the thing that is certain is that the probability is many orders of magnitude greater than that which is verifiable.
This is the basis of my thesis that to be of better predictive value, science has to let go of Ockhams razor, and periodically shift the burden of proof back on to incumbent theories. This thesis is based on looking at science from "the outside". That is, it doesn't use one particular branch of science, to show evidence against a theory from another branch. It doesn't use observations (or amassed evidence) interpreted in the context of current incumbent theories to seed doubt on a high profile incumbent theory.
In fact, it takes an intelligent audience of outside observers who are not invested in the historical sciences, especially the status quo, to notice anything awry. Unfortunately, that limits the philosophical counter check to "Ockham razor science" to theistic philosophies with their own chosen "parsimony" which involves or invokes a God explanation explicitly or implicitly. Thus, the "negative" arguments against historical sciences, should be studied safe in the knowledge that the "positive" arguments as to theistic explanations are doubly "Ockham razor science" and can be safely ignored.
The explanation of why it is scientifically valid, is based on "usefulness". Now if simplifications allows us predictive power, or if the maths works out better or more correctly more often that is one thing. If one is to say that heliocentricity is a "simplification" over geocentricity, this is not what I am talking about.
If the explanation is that a simplification "works" so should be kept until proven wrong, then well it depends on the nature of the falsifiability of the synthesis in question.
Comparing different examples in history, the scientific and philosophical standard that God's omnipotence can explain one or another phenomena is at one extreme which is not generally falsifiable. Pre-tectonic plate theory geology stuck despite statistically damning evidence that continents thousands of kilometres apart were once connected. I don't see why continuing to think that places like the East Coast of South America and the West coast of Africa were "statistically independent" could possibly be "useful" in a geological sense. A theory without a verifiable mechanism that gives statistically useful results ought to be better than a (wrong) theory with an accepted mechanism that does not give those statistically useful results (also assuming that the synthesis is also not predictive or mathematical in nature), thus the former should be considered the best science can offer rather than the latter.
One question I ask of standard evolutionary synthesis is "how is it useful?", how does it "work" would a similar but importantly different statement be just as "useful" and "work" in the same way? My perception is that the mechanism's usefulness is basically self-serving to the naturist philosophy. And if you add that evolution demonstrates and clarifies the inter-relationship between all the species on Earth, mechanism independent statements are just as useful and work in the same way.