I'm sorry you're having to deal with the trolling/vandalism; that can be very annoying and disruptive.
By comparison, Wikipedia/Wikimedia blocks IP ranges including many VPNs from editing, but it also allows editors to ask for an exemption based on their circumstances. Sometimes, this could be an editor from a country that greatly restricts freedom of speech. Other times, it could be someone who is under threats and can't afford to take the risk of someone discovering their location.
I believe most people who use VPNs use them for security. It makes it harder for online thieves and others who would cause problems to locate the person and gather their personal information. If someone knows your name is "John Smith" and finds your IP is in a particular city, they can look up your name for that city and get your address, phone number, credit reports, etc. I advise everyone to seriously consider using a VPN.
Unfortunately, the more security you use online, the more suspicious people may be of you. We live in a time where wanting to maintain your privacy and personal security is suspect.