Why is the coastal crossing theory of migration hard to prove or disprove?

The coastal crossing theory of migration, which suggests that early humans migrated along Coastlines using boats or other watercraft, is difficult to prove or disprove due to the lack of direct archaeological evidence, such as ancient maritime artifacts or coastal settlements. Additionally, rising sea levels over millennia have submerged potential sites of early coastal habitation, complicating efforts to find relevant remains. The theory also relies on indirect evidence, such as the distribution of certain tools or species, which can be interpreted in multiple ways, leading to ambiguity. Overall, the scarcity of concrete evidence and the dynamic nature of coastal environments make definitive conclusions challenging.