Oh, sorry, I think I was unclear or probably even confusing. I didn't mean prosecutors actually just ship off all suspects to the courts with a long list of charges. I meant that they threaten everyone.

Obviously, a plea bargain makes things much easier for prosecutors so their usual goal is to obtain one. However if the accused is sufficiently stubborn, their choice is (a) to assemble a case and prosecute for a few charges; or (b) to assemble a case and prosecute for many charges. I don't think there is a major cost-to-prosecutors difference between (a) and (b) so they go for (b).