I really do think we need to be able to use scale text for button design. We are limited to 6 breakpoints, so for a truly responsive design (particularly at smaller viewport widths on mobile devices) this is essential.
While a workaround is to create a button from scratch - with scale text linked to the relevant destination - this is not ideal. One drawback is that, when I test this method, the artificial button I have created does not seem to work on older devices for some bizarre reason.