Welcome to 5 reasons not to use an engine that you made entirely open and provided all the tools needed to mod that engine in an online game. Oh and how to entirely not secure anything for your users.

I am as much a Fallout and Bethesda fan as everyone else, I've sunk around 4000 hours into Fallout4 and have been making mods for about 2 years. So when I got into the PC Beta and it allowed me to download the client and files, I started playing with them.

Number 1: There are no server checks to verify models or file integrity. Want to make trees smaller, or player models bright colors to see them easier? Go right ahead, here are the tools to do it!

Number 2: Terrain and invisible walls/collision is client side! Want to walk through walls? Open up that beautiful .esm file and edit it. The server doesn't care or check!

Number 3: Want to save money on server hardware and make ping a little more manageable? Go ahead and open up client to client communication but don't encrypt it or obfuscate it in anyway. Open up Wireshark while playing and nab anyone's IP you want! Send packets to the server to auto use consumables, all very nicely and in plain text! Even get health info and player location, why waste time injecting the executable and getting nabbed by anti-cheat when you can get all info from the network!

Number 4: Want to grief people and be a God? Go ahead and keep looping the packet captured in Wireshark reporting you gave full HP. Why would the server care about something as little and not game breaking like this?!?! It's a great idea to let the client tell the server it's state and the server not check anything it's being told! The possibilities with this are endless and probably able to just give yourself items by telling the server you picked it up!

Number 5: Someone in your game being mean? Again have Wireshark? Well let's just forge a packet with the disconnect command in it and knock them offline!

In conclusion: Bethesda should not have just made Fallout76 by throwing mods on it from Nexus and sold it as a new game. Have fun in the wasteland gamers.

Edit: To those crying "lies" and wanting "proof" here ya go the first cheat mod uploaded to Nexus. https://www.nexusmods.com/fallout76/mods/24

Oh wait, it's just lock picking that's still locked behind a card skill/requirement to do higher level locks. However this proves several things: No clientside file checks, and the majority of mechanics are clientside and the server just listens to the client.