Just because you wouldn't abuse it doesn't mean others wouldn't, especially if there were in-game benefits to be had.
You can change hardware ids, there is software that allows it. I'm not super familiar with how HWID works since I'm a software developer, not an IT professional, but there are always ways of getting around these identifiers.
The issue is also this: If you have to create very complex security systems simply to prevent people from abusing a feature, is the feature really worth having? From the sounds of it you'd have more damn code relating to preventing people from abusing the system than the system itself will have in it.
The voting system: People use VPNs, but is it worth it to stop them? No - because it provides more people. A referral system: People can AFK train to 1,000 total level, 24 hours online, change their HWID, and use a Sock5 proxy, but is it worth it to stop them? No, because it provides more people. That's what I'm trying to point out.