It's made tougher because it's p2p, which is a massive negative for players[1]. But it saves them hosting costs.

1: DOS attacks are a very real way that players cheat at these games, to the extent that many highly competitive shooters like CSGO go to great lengths to avoid leaking anyone's IP to anyone else. Everything, including voice chat on the same team, is bounced off of dedicated servers. Overwatch still sees some of this problem as voice chat on PS4 is peer2peer (controlled by Sony, so blizzard can't really fix it), so with some social engineering and fat fingering players can dos the enemy team. So Destiny 2 still doing p2p for crucible is pretty dumb, and if you're a PC player it's a complete crapshoot if you hit some annoying brat that's going to dos you in return.