Why do comments to deleted answers not show up in the activity log?
For example, my comments to an answer to What exactly is a linear space? don't show up in https://math.stackexchange.com/users/27978/copper-hat?tab=activity.
It is certainly not a big deal, but sometimes I use the activity log to track down a thread of conversation or a particular topic, and was surprised that some activity was pruned unexpectedly.