That's ok, I'm just giving an alternate point of view. You don't have to be convinced.
By calling the SMH article a puff piece and only picking the outcome of one petition and disregarding the other 13 you do not make much of a case for your argument, however.
As to your last point, which is important, I'll get back to you. I've made an enquiry because I also want more clarification. Thank you for that.
Here's a couple of items to broaden perspective that show why petitions are useful and have broader implications that are important for democracies. https://theconversation.com/not-another-online-petition-but-heres-why-you-should-think-before-deleting-it-110029 https://www.abc.net.au/listen/programs/lifematters/from-slacktivism-to-real-change-are-petitions-still-effective-/105805264
Over the years I have signed many petitions. Positive outcomes have been because petitions are mostly part of a multi-pronged 'campaign'. One example is the Free Julian Assange petition on your pet peeve, Change.org. I signed the original petition plus just about every other online means of support I could. Julian was finally brought back. I am sure the original petition was not the cause alone but it helped to make the issue broadly dispersed and became an integral part of the campaign as the number of signatories went from tens, to thousands to nearly 800,000. Another is https://www.change.org/p/introduce-arnie-s-law-stronger-penalties-for-crimes-against-pets which you can read for yourself is now closer to being tabled in the Qld Parliament as the petition initiators have been hard at work advocating to MPs.
You seem to want a very mechanical cause and effect. Nothing stands alone in relation to the ways we can benefit our society. It's all process and persistence. Petitions do not solve a problem on their own but are a straightforward tool that can be used to engage people in issues they care about but don't know how to improve on their own. They are also a straightforward way for authorities and advocacy groups to get an idea of what people think. Why do you think our govts are so poll-driven? What people are thinking does matter. Some petitions will never make a difference but some most certainly do.