People should sign this because it raises awareness of the fact that we need people to collect signatures on paper petitions. Online petitions are great, but some states require real signatures on paper petitions. Some states don't even have the petition process, so people who live in states that do have the petition process can help folks in states that don't by getting initiatives passed so surrounding states will be pressured to imitate through legislative action.
A couple of good petitions that depend on volunteers are related to cannabis hemp in Washington state. There is also one for labeling GMOs in Washington state. There are a lot of good petitions going around, some have a lot of money behind them, some don't. I would encourage you to volunteer for a petition that is not receiving a lot of campaign contributions. I encourage you to thoroughly research petitions that receive lots of big campaign contributions.
Check out these petitions
Here is a map that can help you find activists who live near you.