Strategic nomination consists of manipulating a feature of voting systems which lies in their lacking the property of ‘independence of irrelevant alternatives’.
Arrow's impossibility theorem shows that this property is inconsistent with others with more compelling claims to acceptance, and in consequence all seriously proposed voting systems are vulnerable in principle to strategic nomination.
In the limited case in which votes are cast according to positions on a political spectrum, voting systems which satisfy the Condorcet criterion also satisfy the median voter theorem which protects them against strategic manipulation.
An example in the Borda count article shows how that system can be subverted by nominating candidates on one side of a political spectrum.
It is desirable for the outcome of an election to be essentially unaffected by the addition or removal of clones.