I think Seekers main benefit isn't splatting (though you can still get quite a few in the right situations), but pressure. Throw some down a longer passage and they have to switch routes or wait for it to pass. And with enough
and
, you can do this pretty regularly. Port Mackerel's a good example of this, but most zones have some sort of route for it.
You can also use that pressure to splat someone. A Seeker on its own isn't great for splatting, but throw one out and start shooting and people have to pick their poison or stay hidden, and since it inks up, their area for hiding gets narrowed down.
TC can actually work out somewhat well for Seekers. Since Seekers explode on contact, it's easier to hit someone with them on the tower, where they work like OHKO Burst Bombs. But I wouldn't ever pick them over something like Suction Bombs, and since those're pretty common, it's not really worth trying.
Seekers actually can go up the wall in some zones, as long as there's somewhat of a ramp there. It's not majorly useful, but it's nice in some zones. Arowana Mall is a pretty obvious place for this (it's good for most tricks involving Seekers), especially in RM: There are two ramps to the side that usually offer nice perches, so someone is usually already up there and coming down to try to get the RM away from the goal. A seeker up the ramp might not splat them, but you can at least stop them from coming down stealthily, and you can keep them from charging straight ahead from their spawn.
Bluefin Depot is another good spot. That wall with the boards in front of it? Those actually work as a ramp. Again, not a great trick, since it doesn't go up all the way, but in Splat Zones, it's good for closing off an entrance, and keeping a charger a little distracted. And if you can make it up throwing from the far end, you can climb up with a fairly full tank of ink without worrying about getting splatted as you shoot at the wall.
Both these zones have a couple tricks of their own as well: Arowana Mall's ramps can make the Seeker more of a surprise, and Bluefin Depot RM usually passes over a grate by the water, so there's no easy way to dodge them.
Walleye Warehouse is one I'm surprised Seekers don't show up in more often. There's a ramp up to their spawn for RM, and that narrow passage people like, and the extra speed at getting to the center is great for most ranked. You can hide off to the side and splat enemies from there rather than get into the battle and hope you can get around the boxes. Since most of them will be focused on the goal, getting splatted will be a little more unexpected, and you can usually either take them by surprise or get them distracted enough for your team to take control.
The lock-on can be avoided, but like the Seeker itself, you don't have to use it for the original offensive purpose. Hold R before sending it out and look around a little, and you can get an easier way to see any enemies nearby. Naturally, someone could be swimming, but without knowing that they're being watched, they're bound to pop out for at least a little bit, so you can know how many enemies to expect.
And if any of these tricks are new to your opponent, things are much easier for you.
The huge ink cost is a big problem for Seekers, obviously. I usually run a main of
and never realized how bad it got until I was using a new set. I think that and the rareness of Seekers leaves us without many real reasons to try to get creative with them, and so there's not much to try to counter, so it ends up being less useful. The situational-ness of it doesn't help, either. (Hammerhead Bridge is awful for them)
(I've repeated some of these points elsewhere on the boards, sorry for that)