Of course. Take for example mͫ (m+m) there's no way to represent that as a single codepoint. Combining marks can also be overlaid multiple times, e.g. m͚ͫ (m+m+∞) so the number of glyphs you can create is limitless. There's only a tiny number of the combinations that are possible which have a tinier normalized form. The new UNICODE combining marks work by almost exactly the same principles as the \b ASCII combining mark. That's why I mentioned it earlier.