why do scholars feel like Mexico's Gulf Coast was an unusual site for the establishment of a large civilization?

Many scholars feel like Mexico's Gulf Coast was a very unusual site to have a large civilization established because a combination of factors.

1) Geographically it is a very hard area to live in. The Gulf Coast is manly characterized by swampy lowlands punctuated by low hills, ridges and volcanoes. The Tuxtlas Mountains rise sharply to the north, along the Gulf of Mexico bay of Campeche.

2) The Gulf of Mexico is also known for its harsh weather conditions and abrupt changes.

Nevertheless, The Olmec culture flourished here in this area about 1500 BC to 400 BC. But, about 400 BC to 350 BC there was a sharp decline of the population most probably due to weather conditions and river course changes.

Scholars theorize that a combination of these two factors made it almost impossible for a large civilization to have lived here.