There was a lot of talk that 'b' and 'i' was going to be deprecated in favor of 'strong' and 'em' but, it seems that has not happened instead, the definition of when to use which, was updated so, I reckon using 'b' in this case is fine.

In terms of why reset them, this is part of normalize but, we can remove those bits. Might be that some browser set it to different variants of font-weight in their default stylesheets and not just bold so, this creates an even playing field.

i.e.

b might be set to:

    font-weight: bold;

and strong, might be set to:

    font-weight: 600;

or something along those lines.