I have no problem with people who do struggle with mental health issues giving advice and their opinion but I am very, very wary of people who do not look at them as equals doing so. My brothers and sisters who do struggle with these issue have life experiences and insight into these issues and can give very good advice. Those who do not see them as equal, who disregard their opinions because they think "heck, these people care crazy" or look down upon them or try to coddle them or disparage them should not give them advice. They do not need those people telling them who they are and what they should do. They don't need people like that. They are human beings and you treat them thusly.
Like the Latin proverb goes: I am a human being and nothing human is alien or inhuman to me. If you can't see those who struggle with these issues as nothing but another human then step out of the way, if you see them as insane or crazy and therefore as less than human then you have a problem not them