Why set a class for everything?

Question

BEM

First option

<nav class="navbar">
   <ul class="navbar__list">
        <li class="navbar__item">
              <a class="navbar__link" href="#">About</a>
         </li>
    </ul>
</nav>

Second option

<nav class="navbar">
     <ul>
           <li>
              <a href="#">About</a>
            </li>
      </ul>
</nav>

Why, according to the BEM principle, it is necessary to specify a class for all elements, but we can style it just like this:

.navbar ul li a {
   color: #fff;
}

Instead of

.navbar__link {
   color: #fff;
}