That is true. And as we know from studying the texts themselves, the artwork based on them, and the doctrines they contain—such as the ever-important Dasapāramī and Dasavidharājadhamma —a fair argument can be made that they rank among some of the most important and influential texts in all of Buddhist history.
We have been discussing how important they are in another thread here (and thank you for your contributions there, Robert):
I mean, even as recently as 2017, the funeral rites of King Rama IX included sermons on the Dasavidharājadhamma. That shows how influential they still are. And we know that the primary sources for the tenfold virtues of a ruler are the Jātaka and the Jātakatthavaṇṇanā.
And if that’s the case, how influential do people think the following words have been on Buddhist rulers throughout history?
“Dānaṃ sīlaṃ pariccāgaṃ ajjavaṃ maddavaṃ tapaṃ / akkodhaṃ avihiṃsā ca khantī ca avirodhanaṃ.”
And that’s just the Dasavidharājadhamma! It says nothing of the influence the doctrines of the ten pāramī and everything else contained in the Jātakas have had on people.
I find it baffling when people scoff at these texts. 
R