Well, because it's a philosophical assumption, not a scientific theory.
Science is what we know: Philosophy is what we don't know. We know that at one time there was no life...then there was. Abiogenesis is the only scientific explanation, sorry.
Those claiming that "abiogenesis is the only scientific process" need to be able to specify the process. Otherwise the word is empty and isn't informative.
I get the impression that you are playing a little slight-of-hand card-trick I suspect that you are confusing yourself.
Not at all. It is fact. Once there was no life: Then there was. Abiogenesis is the only scientific explanation.
That doesn't exclude the possibility that life had an origin that wasn't naturalistic and that explaining life's origin might be entirely outside the scope of natural science.
That actually appears to be a sleight-of-hand trick, to legitimise ID. It doesn't.
So methodological naturalism doesn't seem to be suitable for your rhetorical purposes.
My claims are more scientific naturalism, rather then your own philosophical rhetoric...evolution of spacetime...Superforce...phase transitions and first fundamentals...atomic nucleii....first elements H and He...stars ...heavier elements...more stars and planets...
Life.
Then slippy-slide over to the idea that any true and correct account of life's origins must necessarily be scientific and hence naturalistic (metaphysical naturalism) and you seem to think that the evil ID'ers are defeated.
Actually, that's back to front. It's us poor deniers of ID and creationism, that generally and are labelled as "evil Atheists"
In essence your apparent fence sitting, has your legs obviously dangling over one particular side.
Which I suspect is your goal in all this. I don't think that it's working.
I havn't a goal actually. What you believe is your problem. I'm simply stating the fact that Abiogenesis is the only scientific explanation of life, and that any possibility of non scientific nonsense, requires a belief in ghosts, goblins supernatural and paranormal activity, which is all unproven and unscientific.
And of course any ID or creator need by definition to defy science and logic explanation, with such unscientific properties/qualities, as omnipotence, all powerful, and the rest of the nonsense that such non science explanations require.