My opinion is that this is because most of the members of this forum behave very irresponsibly towards such things, and I believe that many are not aware that there is an option to close the topic or that the topic can even be moved to another board. If we take into account that this is an excuse for those I have already mentioned, what about those who are aware that such topics should be reported to the moderator and prevent them from turning into signature spam megathreads.

There is an answer to that question, and it is very simple "reporting is a waste of time", and that is unfortunately the official position of some very influential members of the forum.