But of course incumbent bias is still dependent on the candidate not being unpopular.

I can see arguments for term limits, particularly in positions where the composition of the electorate means the other major party isn't likely to seriously challenge the governing party's preferred candidate (usually the incumbent) which makes their position very safe indeed.

But anti-corruption isn't one of them. Arguably, from a point of view of anti-corruption, the incumbent needs the special interests a lot less than the new challengers...