This not only buffs the damage capabilities and survivability of your merfolk, but it also allows them to more easily deal damage without being intercepted by blockers
Also there are cards that have different font used (Candelabra of Tawnos, Tarmogoyf MM) or different spacing and leading (Flooded Strand) which should give away the cards at first glance
This can be a bit of a bummer if someone interferes with your plans, but Snap is still a very flexible removal spell that has its uses even when opponents aren't presenting threats
And when we were over there playing with them and hanging out at the Square Enix offices doing work, after hours, well play a commander or play Magic together
All told, the sorcery speed of this card probably holds it back more than the potential for it to be dealt with and the consequential aversion to targetting EtB effect creatures with it
Some of the better cards included in these sets are Cyclonic Rift, Praetor's Grasp, and Sword of Truth and Justice