>>527242205
There is no reward to killing leviathans. They're numerous, constantly respawn and are easily avoidable. They do not pursue you, they only shoot at whatever enters their line of sight, they follow a predestined path from one map border to another.
They make vehicles of any kind impractical to use due to their tendency to instantly kill vehicles and the large areas of the map they can see at any time. In this way they also punish cooperative play in the cooperative game, it encourages the team to split up and complete objectives individually rather than everyone getting held up by a leviathan by traveling together.
Their projectiles are fast enough that they're effectively hitscan and impossible to avoid.
Engaging them at all merely wastes resources and vast quantities of time and leaves you open to randomly being instantly killed by them.
I quickly realized that engaging with them at all was a lame and pointless risk when I could just ignore them and be doing something useful.