The coastline paradox is often criticized because coastlines are inherently finite, real features in space, and, therefore, there is a quantifiable answer to their length.[17][19] The comparison to fractals, while useful as a metaphor to explain the problem, is criticized as not fully accurate, as coastlines are not self-repeating and are fundamentally finite.[17]
I believe they were referring to this, where technically a coast could be seen as similar to fractals
https://en.wikipedia.org/wiki/Coastline_paradox
Literally from that page