When draw order keys are always there, they are easily moved or keyed accidentally.
The filter is an option, but using it to hide draw order or events then makes it slightly harder to use the filter for other things.
We have a number of "global" timelines now that aren't associated with a specific bone: draw order, events, and physics global inertia, strength, damping, mass, wind, gravity, mix, and reset all. Showing them all the time (if they have keys) adds clutter to the dopesheet. For physics we only show them if a physics bone or constraint is selected. Now for draw order and events we have the same option, but only if you turn off visibility for the draw order and event nodes in the tree.
