Trailer manufacturing ( winch post) is unfortunately,self regulated.The post, and the tie down, are important, if you get into a minor accident. It does not take much, to dislodge your boat , especially if you dont tie it down, in some form,and of course, the stronger the better.
However ratchet straps,dont just have a downward pull,that is why I went to the cross bar,and a straight down pull.Even then you have to be careful, with the sides of the boat.
If you have not experienced it, it really is easy to move a boats position,on a trailer,if it is not secure.
David