Hallelujah. Preach it brother! When I did an app a few years ago and it needed to print (http://paperquik.com) was when I discovered what a god forsaken mess it is. I encountered and still have all the margin problems and I also discovered how messed up printing of SVG was in virtually every browser.
I wrote about that problem here: https://johnmunsch.com/2013/09/01/using-svg-to-make-custom-paper-and-why-it-didnt-work/
I managed to find a different solution to creating the material I wanted to print and get it to print at sufficient resolution, but I never found a good solution to the margin problems, nor things like Firefox’s desire to put page headers and footers on everything.
A real, long term solution would be for a site to be able to offer some printer settings and the user accept or refuse those as they do so many other things within the browser. For sites to have absolutely no control over printing is not viable for the future, especially with the number of apps we’re seeing move online.