I tried this kind of selectors for styling and I don't like it. I can explain why with a question :

What if you want a button that looks like a like and a link that looks like a button. In your case you will have to overwrite "button" selector, which is with very high specificiy and to override the main selector styles.

    button.link { color: white; border: 0; background: none... }

and then copy the relevant for only a link styles to your link selector ( a ).

This works good for small code base, but once you go to several pages and need specific links it starts to make a lot of problems.

I stopped using this way of styling buttons not so long ago and I switched it to :

    <button class='button'></button>
    <button class='button button-primary'></button>
    <button class='button button-danger'></button>

And also for links

    <a class='link'>Link</a>
    <a class='link link-primary'></a>

And then I can easily switch

    <button class='link link-primary'></button>
    <a class='button button-danger'></a>

without touching my code.

Same applies for input[type='...'] rules. I just add class name.