Most trading signals aim to exploit a secret edge. A temporary market inefficiency. The value is in the secret itself. Once you sell the secret, the small window of opportunity is competed away almost instantly.

Trend based models are different. The "secret" isn't a secret at all. Think of a trend based trading strategy more as a disciplined methodology. Trend based models follow price and attempt to identify as early as possible when an asset flips from bearish to bullish.

Therefore, selling our model wont destroy the underlying trend, especially in highly liquid assets, such as: SPX, BTC, etc.