Destiny 2's netcode may be an engineering marvel that saves them some money on dedicated servers, but it sure undermines the game experience. It was a problem in Destiny 1 also - people exploited the P2P nature of the netcode & design flaws to cheat at multiplayer content and in exclusive content like raids to harvest rewards. People would manually firewall off their PvP opponents' IP addresses to harvest free wins, and in the PvE content they'd do things like have the current host disconnect to break bosses' AI and make them easy to kill. The P2P netcode also results in enemies teleporting around and glitching in difficult content, which is INCREDIBLY frustrating.

In 2 I haven't seen as many cheats of this variety, but they remain possible. The real problem is that the multiplayer is a trainwreck: Loading into towns and open world areas can fail because the P2P host's connection is bad, and any time you travel more than a few hundred meters in the open world, all the other players vanish because you get booted to a new host. In practice this means that you don't get to interact with other players for more than a few minutes, AND you can only bring two other friends into the world with you due to the limited party sizes.

As an engineer I can totally understand these constraints but the game experience just sucks. I can swap over to Playerunknown's Battlegrounds and get dropped into a 100 player match after about 10 seconds in queue, but joining a 4v4 PvP match in Destiny 2 takes upwards of a minute. The game's multiplayer aspects just feel incredibly dated. Despite this, the content is all tuned for multiplayer - the strikes and heroic public events are nearly impossible to complete solo, and the main sources of powerful gear (nightfalls, trials, the raid) require 3-6 players with good connections that can stick around for an hour+ without getting disconnected from each other.