Actually there're a lot of suttas that explicitly spell it out. Let me know if you find any sutta reference mentioning stream entry with the existence of the 3 fetters.
I can see the drift of your mind here, but you should know that the absence of positive evidence that the 3 fetters are not needed is not proof of the fact that they are needed.
On the contrary, the absence of the statement that they are needed in suttas such as the one I quoted above and the similar ones in that samyutta and elsewhere, where the requirements for assuming one is a streamwinner are explicitly spelled out in the absense of any mention of the one-truth [or own-body-] view, or the inadequacy of ethics and rituals to in the task of ending Pain is sufficient proof that they are not required.
To say that Gotama forgot to mention them when they were in fact required, would be to accuse him of a grievous error, giving people false hope, and falsify his claim to have taught the Dhamma well.
The term Sotaapanna means 'stream-enterer'. One who has entered. The stream is the course leading to Nibbaana which is against the stream of the ordinary person. Entering does not imply having crossed. Entering the stream is what happens when a person for however slight a period recognizes the problem of rebirth and of persuit of that which changes and sees in Gotama's Dhamma a possible solution.
On the one hand the tendency to speculate is encouraging in that even this much is sadly lacking today, on the other hand a more fruitful approach would be to put aside the tendency to speculate and use in stead the technique of trial and error. Try to understand what Gotama said in the words in which he said it, let go trying to reformulate what he said in the terms you understand. Baring wrong translations you will find that what Gotama has said was well said precisely as he said it.
I am sorry I will be unable to pursue this dialog futher with you as tonight is my last night connected to the internet. I wish you and the other seekers here the best of luck and progress on your journey.