That's the nonsense about it. Mutations are defects. Even genealogists have said maybe 1/10,000 mutations could be beneficial to an organism. However, many mutations (defects0 are harmful to the organism or even deadly, that that this organism must go throw the 9,999 negative mutations (that would be futile and deadly) before it got a chance to use one good one. Chance would not have a chance. Chance btw, has no power, no knowledge, intelligence, direction ... chance is nothing. And to think the nature could select ... wait a minute, let's stop there. What is nature? Water, minerals, the sun, electromagnetic energy, etc. None of these has a mind nor collectively do they have intelligence to select anything. The organism itself (if it could possibly evolve) could not select it's own defects, log them and then pick and choose the good to pass them on to their offspring. Remember, mutations create distortions, weaknesses, deformities, not more complex or more advanced abilities or structures.
See how absurd it all sounds. It's a theory made by a bumbling fool who was not even aware of the complexities of a cell. Darwin thought a cells was a jelly-like substance, simple. No cell is simple. If you blew one up to 10mile radius, you would see thousands of intricately designed molecular machines and made up of 100 billion atoms. It is far more complicated than anything man has ever made and that's one cell. That does not even begin to discuss the complexities of organs within systems and all dependent on each other for life. Organs and systems can not be put together in a piece by piece order over millions of years. The eye for instance needs all it's components to function. All would have had to evolve simultaneously in one perfect moment for vision to work, be beneficial and then be passed down.
Besides that, there are no transitional forms, just imaginative hopeful candidates, illustrations that have be drawn to suggest how things evolved.
Your question is even flawed along with your theory. It should have been more specific, addressing only Macro-evolution, species turning into entirely different species. Micro-evolution is obvious, things change within the species. But these are adaptive mechanisms already programmed into the code. That's right programmed, by a Designer.
You wouldn't expect the iPhone in hands just appearing by chance, non-intelligent means over time???
Your theory is similar to an explosion happening in a print shop and the Encyclopedia Britannica appearing by chance as a result.
From slime to Marylyn Monroe -- all by chance, defects collected over time -- LOL.