Everything is in the title. For now, I stop answering questions, it takes me too much time.
So if I understand your post correctly, the problem you see is that answering takes a long time and the reason is that you don't have macros automatically at your disposal. (Of course, for other users there might be other factors which slow them down - but it seems that you have singled out that this particular things as a problem for you.)
If you have a few commands which you are used to and can't really efficiently write without them, you can simply copy-paste a block of newcommands at the beginning of the post. It is probably not an optimal solution - but I've seen users who do this. (Although this probably won't be feasible if the macros you need are in the range of hundreds.)
If this would be possibly useful for you, you could check also this post: Bookmarklet plugin to speed up LaTeX macro typing. Although it might take some time to get used to shortcuts implemented there. (I don't really know how difficult it would be to add your own shortcuts to the list.)
Personally, if I have at least slightly longer post I do not write it on site - I use an editor on my computer. The advantage being that I can used the keyboard shortcuts in the editor which I am used to.
I will also mention that I use newcommand in my post relatively often, especially if something repeats rather frequently in that particular post or if I am copy-pasting some parts from LaTeX source which I have used for some other purpose. In such cases, I checked which macros are needed when I am done and I include only those. (It's a bit of nuisance, but in some cases it outweighs the need to type longer expressions that can be shortened by the use of macros.)