Why I shouldn't load pdftex option with hyperref?

Question

According to @percusse in this post, I shouldn't load the pdftex option with the hyperref package. Why is it?

Answer 1

I would say you won't need to tell hyperref as it detects this on it's own. If you load hyperref by

\usepackage[pdftex]{hyperref}

and use another engine like XeTeX or LaTeX+dvips it could cause errors as hyperref adds \special commands to do its stuff.

These \special commands are different with each engine (pdfTeX produces PDF immediately—so no \special is neccessary—while dvips for example won't and therefore needs those \special commands in the DVI-file, created by LaTeX (or TeX). These \special commands will be processed by dvips to realise the features of hyperref).

All possible engine drivers and more information is provided by the hyperref manual.

I think you should only use those option only if you get trouble by processing your documents. But be aware of it, if you might change the engine.