Darwin's reasons are cryptic, brief. He was more interested in natural selection and so on.
So we must look elsewhere in the consideration of origins. I don't think questions of origins are unimportant. For example, I think it is an profound conclusion to say certain aspects are unkowable. But this much is clear to me: the study of biological processes can proceed without a theory of origins; but this is no reason to say that life originated independent of biological processes.
I think you need to give this part a bit more thought. Try reading some stuff by actual researchers so you will at least have some common ground for discussion.
It is important to keep looking even if it is logically unknowable - simply because so many people are curious about origins. Also, I believe it would be wrong to dismiss discovery out-of-hand, i.e. only look to laboratory experiments. Who knows what observation technology may arise in the years to come?
But I very strongly assert that abiogenesis investigations should not repeat the Urey/Miller omission, i.e. they were not aware of the information (successful communication) component of life and were only able to produce about a dozen amino acids. IOW, they looked for a physicochemical solution only. The Wimmer experiments on the other hand began with the DNA message and were successful in bootstrapping the polio virus.
The investigation into abiogenesis v biogenesis must be wide to include all the non-spatial, non-temporal or non-corporeal factors that can be considered (information, geometry, autonomy, symantics, semiosis, etc.)