There is only one way to make a set necessary, and that is by printing new cards that are required if you want to win
So a regular counterspell won't cut it, it will require something like a Disallow being used, but this will only deal with one half of the problem - either the body or the ability
Expect that card to dominate the English sets singles market when release day hits
I get what you're saying about the Legacy deck idea, but the fun for me of Magic is the changing environment and trying new ways to win
Whale, combined with Three Steps Ahead can lead to some pretty swift turn arounds, so you don't have to waste slots in your deck for other win conditions besides your lands like Restless Anchorage and Fountainport
I only played against AI opponents in my time with the game, but if you want to play competitively, you wont get demolished in the first turn