I have a couple DSLR's and a large frame compact, and I wholly get your point. The image quality on even an older DSLR is better, mainly due to the physics of the optics - there's nothing like a high quality lens dumping a bunch of light on a large sensor.

However.... it's really hard to overstate the workflow and convenience aspects of shooting with a phone. (Particularly as a parent, and even moreso when I was a new parent of a small child.) The phone has the twin benefits of 1) being present almost always and 2) being immediately able to process and transmit an image to the people you might want to see it. For the 99% case, that's far more useful than even a very significant improvement in image quality. For the 1% where it matters, I can and do either hire a professional (with better equipment than my own) or make the production of dragging out my DSLR and all that it entails. This is like so many other cases where inarguable technical excellence of a sort gives way to convenience and cost issues. IOW, "Better" is not just about Image Quality.