Today, Atropos is fast, accurate, and powerful. Atropos is like a super Harpoon - they kills things easily! I would like to mount them (and light needlers and other rare and powerful weapons) on a lot of ships, and I do have dozens of ships by endgame. Atropos is rare, unfortunately.
In earlier versions that featured Logistics, Mercury was worth 0.5 Logistics, and with 100 Logistics maximum possible, you could literally have dozens of them (in theory). Mercury has terrible stats, and cannot use ballistics or energy weapons very effectively with poor flux stats. However, they have universal mounts, and can mount missiles. With only missiles, Mercury does not need to bother with flux much or need to add otherwise mandatory hullmods like ITU. The idea is to deploy a Mercury-turned-missileboat, kill a few ships, then get out. Repeat until enemy fleet is dead.
Atropos was not very good back then. Usable with max Missile Specialization, but otherwise outclassed by better options. But, Mercury with up to twelve Atropos can kill two or three ships before needing to retreat. All at the cost of one 0.5 Logistics ship.