They are both general purpose formats that arent optimized for games.
What does it mean? it's the artist which optimizes the model and decides how the model is created, not the format. If the file is interpreted correctly and then converted to the engine's proprietary format it is as good as a conversion from another format of your choice. Once converted, the model would only keep the information which you want it to store in the proprietary format. Anyway, collada actually was made for games, even though it isn't as mature and supported as fbx. From the abstract complainings this discussion makes me wonder how many of the people who is arguing against fbx actually had some complex work converted with it, or used it at all. I know for experience that it works well enough. It won't make your geometry, boning, and mapping correct by itself though, so you still have to know your stuff (or modellers limits) before blaming the result. You can't except to have a converted vue scenery working out of the box in your engine, for example, or to use node materials in lightwave instead of baked maps and expect fbx to keep them intact after exporting.