I find it objectionable as well when some scientists overreach as well, ascribing to ToE as complete in itself in explaining all knowledge possible about the development of life when an important aspect is beyond science's capability to describe.
I too would find that objectionable. Moreover, it's bad science to make such a claim.
Few serious scientists would ever pretend to have "all knowledge possible" about any subject whatsoever, much less a subject as complicated as the development of life on Earth. If you have in fact heard that, you must understand that what you describe represents an extreme minority in the scientific community.
I'd be very interested as to who exactly said that evolution is "complete in itself in explaining all knowledge possible about the development of life." No offense, but that sounds much more like ID propaganda than the actual position of any scientists.
Oh, scientism is alive and well. To find a scientist that proclaim science can completely explain the development of life one need look no further than Richard Dawkins.
He teaches that all life is the product of purposeless material forces-random genetic variation and natural selection.
I think we could both agree that when science begins ascribing purpose, or purposelessness, to its field of scientific study, it has crossed the boundary of what science can know, or claim to know through the use of science alone.