I haven't ever used it, never signed a petition, but isn't change.org only about petitions? I can kinda see their reasoning.. They may even have had their hand forced to do it.
Loads of people who want their way probably signed up with tons of accounts to skew the results. If it's going to work, I guess they need to be able to show that they're legit, out at least that change.org are doing their best to make it that they are.
It's easy to set up one gmail account for example and use it a million times with moving a dot throughout the name or putting a plus sign and anything after the username but before the @ symbol.
I'm surprised anyone uses Google services considering how they infiltrate your privacy.
A Google VPN is as private to me as giving a six year old a cardboard box and asking them but to look inside.