So in the short term, reading on monitors will still be hard. 5 years from now, it should start improving. One truism about reading on the web is that people don't read, they scan. If there are already 2 subtitles fighting for attention, you don't want to highlight elements in three different paragraphs as well, because if too many things are fighting for attention they all loose . Proper page labelling is an art in itself.
Subtitles are important for scannability.
People don t read webpages, they scan them, and we should write to assist this scanning. Subtitles can help. Highlighting important concepts can help too, but there s an art to that. In the beginning I tended to highlight groups of words, but now I tend more towards highlighting sentences. Find your own style.