I mean, for some of them yes, like the Grand Inquisitor, Fifth Brother and Iskat, but others had no choice but to join. I don’t think it necessarily makes them weak, like how even strong Jedi like Cere used the dark side after being tortured and in Cal’s vision he was an Inquisitor even though we know he would’ve never done that if he were in his right mind. It’s also important to remember that many Inquisitors who were tortured into joining were padawans, which meant they were young and probably more susceptible to brainwashing.