How is the readability of a blog without titles? Difficult.
When you see a home page of a blog with a list of postings that have pictures and summaries but no titles, it's hard to know if or where you want to click though. If you have to invest the time to read the summary for each post, your clicker finger just might get antsy. Yet the cursor is likely to go off in search for easily digestible and better organized food for your mind.
Note: Do use titles and subtitles in writing pieces. They keep the reader interested or let them know to go elsewhere quickly.