To make sure that the links posted on this forum don't transmit private informations,
How is it that a link posted on this forum would ever be able to transmit private information? I'm not sure I understand the concern...
Also, some sites contain both useful info and pure disinfo, and cannot always be blocked by site address alone. Take Youtube for example - a video link might need to be _'d out, but other videos we may actually want to link to properly.
At least using the '_' system, one can see the source website, and then make a decision whether or not to visit. Otherwise, you would have
to click the scrambled link, just to find out where it goes.