While true, I don’t think this would happen as often as you might think.

For example, lets say some nefarious actor starts some comment thread and later decides to delete their comment “to own the Libs” or whatever they say now. That entire threads responses were meaningless. They were argumentation and flamefighting. If the comment information was incorrect, removing it as a deleted comment is more beneficial than leaving it up for others to read and ignore the context.

Lets say someone decides to delete their entire account and comment history. Reading responses are going to be difficult to understand the context. Most of the time these responses are to specific issues or comments, not typically a general answer, as general answers are usually top level comments. In this case, if someone later has the same question, it can be answered again later when that person asks. There may be more updated information between then and the hidden reply that changes the information, and there is no need to retain outdated answers to a question.