What do they want? Maybe the “good old days” where confessions were tortured out of people? They still have that option, it is called lawfare. Trump is experiencing it right now.
There is a reason that “Innocent till proven guilty” was enshrined in law.
Many countries it is “Guilty until proven innocent”. Basically, if accused of a crime you have to prove you didn’t do it.
As we slide away from the bill of rights, the judicial system is more the latter than the former. Pleading the 5th will be taken as an admission you have something to hide, and be presented as such.