** I agree with you with regards to having to change or create breakpoints for every page over and over again but in some cases there is a good use for it and I got to agree with Wix that developers would prefer the control of having to set the breakpoints of each page than to have one universal breakpoint for all pages.
** I believe setting anchor or element in a master template is a good feature request, so I hope Wix EditorX team consider this but for now we have to understand that EditorX is still in its beta.
** By default, the canvas tries to load in “100 vw” which is annoying sometimes I agree, but I have found a work around it. Unless you are building a website with infinite width/full width, I suggest you dont make the canvas the main element container. I first add section and allow it to be full width, then I add a container, the container is what I set to my max width of the page and all my designs go into the master container, this helped me ignore the issue but I hope Wix does something better about it.
** I understand your frustration.