There are a couple of things I could say I'm an expert in. Math and deaf education, for instance. I have the degrees and the training, plus actual years in the classroom. (Not that I can't still improve, of course.)
Then there are areas I have experience in. Some coincide with my expertise (such as those years of experience in the classroom), while others are just experience, making me far from an expert. I'd put writing and the publishing industry in this latter category, though I think it's transitioning to the former.
I have expertise, I have experience, and I also have opinions. On just about anything. Some of those opinions are on subjects I have NO experience in, much less expertise. I try to make it clear that those opinions fit into the "very theoretical" category.
My opinions on writing and publishing are a little less theoretical, because I've actually done some stuff. I've written a few novels. I've queried a lot. I've critiqued a few manuscripts, and I've talked to some agents and editors. But in a business as fickle and subjective and super-in-flux-right-now as publishing, my individual experiences are only worth so much.
Still, people ask for advice. I offer my opinion, and I try to back it up with the reasoning or experience that led to it. They can take it or leave it as they see fit.
That pretty much goes for all the advice and opinions I offer in any area, including education. Yes, I favor certain ways. Yes, I get frustrated when other people seem stuck in what I view as outdated or unsubstantiated opinions. I get even more frustrated when those people don't have the expertise to back up what they're spouting.
I'm pretty sure beating someone over the head with what I think won't do much to change their mind.
So I'll say what I think, especially when asked directly. I'll try to keep my mind open to understanding the reasons behind opposing views. And I'll give experts a fair shot, while considering the source of their credentials.