Technology needs wisdom and responsibility. If time travel is possible then responsibility will be an issue of great importance, but might easily be overlooked. Time travel might be a science that allows travelers to behave as gods in the eyes of the people they visit. Something that will not be without consequences.
Successful sending messages to the past will definitely change the past. It might be a relative small change, like people staying home to think about the message instead of going fishing, but there will be a change. Changing the past must be something undesirable and to be avoided as much as possible.
A prophet could create a book of prophecy containing wisdom and values based on messages received from the future. The existence only of such a book of prophecy might lead to changes in the history time line. No matter how well the message has been meant, it still might have tragic consequences for the future of the receiving world.
A book of prophecies might have a number of interpretations; each interpretation can have its own group of followers or even lead to the rise of religions. It is possible that the existence of such a book causes violent and destructive conflicts between the different groups. It can lead to persecution of one group by another.
The consequence of sending a message is not predictable before the message gets sent.
It is possible that a change in the course of history does not affect the present of the sender. But still it is the responsibility of the sender to avoid that the messages sent, causes changes in history that might lead to suffering in the world of the receiver.