Yes, you know, people do post things online as well, I've read them, that alcoholics need support, love, stability etc (don't we all)!
The thing is, he is sick and he does need support, she's not wrong, BUT the support he needs is nothing a layperson can give. He needs professional support, not just people walking around on eggshells to avoid being screamed at and dinner on the table on time and the children being seen not heard (preferably in their rooms).
What is that "support" they speak of? I think that is always the missing component when people talk like that. Unless you are trained in the field, how can you give support to someone in active addiction? That is why AA evolved, that is why there are thousands of rehabs, not because spouses/mother's/father's and siblings are not "supportive".