Summary: This paper is devoted to the complexity analysis of a particular property, called geometric robustness owned by all known symbolic methods of parametric polynomial equation solving (geometric elimination). It is shown that any parametric elimination procedure which owns this property must necessarily have an exponential sequential time complexity even if highly performant data structures (as e.g. the straight-line program encoding of polynomials) are used. The paper finishes with the motivated introduction of a new non-uniform complexity measure for zero-dimensional polynomial equation systems, called elimination complexity.