There are also similarities between 2003 and 2017. In 2003, Powell's presentation at the UN spurred on the invasion of Iraq. Haley's 2017 presentation was meant to do the same thing, drum up international support for US intervention but it did not materialize. The US launched 20-odd Tomahawk missiles in response (the stocks of boeing, Lockheed, raytheon spiked.)
So, yes I think you're right in saying it's a case of the boy who cried wolf as there was little support for a war with Syria despite Haley's performance.

Powell's so called evidence was essentially sexed-up intelligence reports that turn out to be not so intelligent. Yet, I think that in Syria these child victims of the 'suspected chemical attack' are certainly real victims of the proxy war but it's extremely difficult to say who and what really killed the civilians in Douma. However, a year on it has been reported that a BBC producer admitted that the chemical attacks were staged.

https://www.mintpressnews.com/bbc-producer-says-syria-douma-chemical-attack-footage-was-staged/255152/

All this to say that these two UN presentations were designed to push for war which as we know ultimately benefits the defense contractors.