Responsibility is just one of the factors. The others (according to HSE-sponsored research) are:
organizational function and culture,
role in organization,
career development,
decision latitude/control,
interpersonal relationships at work,
home/work interface,
task design,
workload/work pace,
work schedule.
People don't always have a choice (it's also highly stressful to be unemployed) and employers increasingly have a duty of care not to cause illness related to stress, at least in some countries.
Suffering or not suffering from stress is not 'simply' a personal choice one can take, given sufficient backbone or control: have a little sympathy - any more than an asthmatic can simply snap out of it when told it is often due to psychosomatic reasons.