What are the shortcomings of ecological pyramids in the study of ecosystem?

(N/A) Ecological pyramids have several limitations in the study of ecosystems:
$1$. They assume a simple food chain,which rarely exists in nature. Most ecosystems have complex food webs.
$2$. They do not account for the same species belonging to two or more trophic levels simultaneously.
$3$. They do not provide a place for saprophytes,decomposers,and parasites,even though they play a crucial role in the ecosystem.
$4$. $A$ given species may occupy more than one trophic level in the same ecosystem at the same time,which is not represented in a standard pyramid.