I have Elements 9.5, which come with a limitation on the number of tracks. Adding 16 midi tracks would eat quickly through that limit.
Besides, it’s also unpractical. Suppose I have a VST instrument for a symphonic harp. The 7 different ways of playing it are stored in 7 separate VSTIs in their own right (full keyboard). Should I create seven MIDI tracks for each of these VSTIs? That would take up a lot of unnecessary screen real estate, not to mention muddle things up. Also, some of these VSTIs will be used perhaps once in a piece, but require a whole track.
Being able to use them all (be it only one at a time) on a single track would be much more concise and practical.