While you can get blown out before this has a chance to do the thing, you can just play some counterspells and a Mirrormade and hope for the best
Adrix and Nev, Twincasters and Thrasios, Triton Hero are great examples of powerful merfolk that work without being part of a dedicated typal deck
Kaheera, the Orphanguard With many companions banned in the most popular Constructed formats, like Jegantha, the Wellspring, Lurrus of the Dream-Den, and Yorion, Sky Nomad, options are limited, but Kaheera, the Orphanguard remains solid for control decks
The print run of Unlimited was way bigger than the print runs of Alpha and Beta
And, whats more, there will always be those decisive cards that overperform for you that it feels criminal not to be playing