Since I've trained different MAs practically my whole life, I really don't mind admitting that no one art has everything. Some arts are more versatile, but that's it. And I don't think that it's disrespecting your art to admit that. I do think it's important, and even essential, to have a base art; one or perhaps two arts that form your personal nucleus. For others, only a single art/system will serve their MA needs their entire lives, without any need to go outside of that, and that's okay, too. Most people don't even train one art, much less stick with it for years and years.
Nobody can honestly say that any one art has it all. And anyone who would loudly argue that it does simply has an agenda or hasn't experienced enough.
As far as to argue or not to argue, sometimes it's entertaining, to a point. IF something useful comes up. And sometimes arguments run on and on, but very little is actually said. Would you prefer quantity or quality of discussion? If someone says "X art sucks," beyond maybe a couple responses to that is a waste of time.