And that is probably the best argument that time travel is impossible. For if it was, we would already have been visited by travelers from the future.
That argument certainly eliminates the possibility of traveling back in time. If traveling forward in time is possible we won’t hear about it until it’s invented. Even then only those who use the technology will know if it works.
Oh no! I think you just opened the door to the time traveler posters ... :-) ...