More than that, as part of LINQ they built a whole "expression" engine into the language to make LINQ to SQL more powerful than simple method chains could be. What looks like function calls is actually converted into expression tree at the language level before conversion to SQL statements when communicating with a DB backend.

The method-chains-vs-expression-tree semantics don't matter much when doing typical in-memory map/filter/reduce on lists but make LINQ to SQL and other more complex use cases much more powerful.