I believe the buttons are correct - a signup with a modern startup web software (ie. an app) feels much less like "starting to use our software" but more like "sign up for this email campaing we're running". Signing up usually requires an email address and then results in "Greg from Blahblah-App" follow-up emails. To me it feels like many startups are truly so desparate for some users, that they will follow "best practices" and spam the hell out of anyone who will leave their email address. I am not a fan of this culture.