Good point. But when the search for natural causes gets to the origin of life, it stalls out.
If we abandonded research that stalled out in the past, we would still be banging rocks together.
There has been no naturalistic answer in the half century since discovering the structure of DNA. The reason is that, at the level of the cell, virtually all of the molecular systems exhibit irreducible complexity, and the code embedded in the DNA sequence is something that can not yet be explained without positing an intelligent designer.
Sorry, but a God of the Gaps is the most horrid argument I have ever seen. If there is a God, he has to be insulted by it.
We tried for hundreds of years to produce machines that flew. We couldn't do it. Did that mean that fairies kept birds aloft? This is the type of logic you are using.
For the Biological research establishment to admit that, scientifically speaking, there is room in the origin of life for an intelligent designer, would require an admirable example of scientific self-criticism.
No one is trying to exclude an intelligent designer. There just happens to be no evidence for one, and even those who claim that there is a designer fail to do any research to test the idea.