I don't know about you, but changing any font takes along time, making sure leading, tracking, size, how it looks, line length (or number of words per line)...
However To physically change (without considering all the effects) a font on google fonts takes 10 seconds... it involves changing one URL and then the font stack you are using.
Changing using fontsquirrel takes a couple of minutes, download the new font-face kit, upload it to the server, and change the stylesheet. Sorted.
So I'm not sure how typekit (haven't used it) is any quicker