Errr, using <large>, <strong> etc, is fine. In fact, it would be incorrect to use CSS for such a use. You shouldn't create some sorta span to just to
bold this word or to
italicize this one. The articles you are reading are probably referring to pages where all <p> or all <h1> are additionally <strong> or <large> modified. If you want to bold your headers or your text, do that in CSS.
Another thing you might have read is about <strong> vs <b>. Any html tags that just specify the appearance of something like <b> (bold) or <i> (italicize) should be replaced with tags taht have more semantic meaning like <strong> and <em>. They will appear the same (at least in most mainstream browsers), but will also be usable on all sorts of displays. For example, if it is some sort of html-to-speech browser, you might drop <b> assuming they are just appearance tweaks, but you wouldn't drop <strong> (you might have the broswer read the word with emphasis....errr... that <em> but close enough).
(the <large> tag probably falls under html tags like <b> and <i> that are deprecated because I can't think of any english semantic for it other than "display larger")