Yes, those who don't have the knowledge should listen and learn, rather than post.
But even though many of them don't follow this advice, it's still quite possible to separate the wheat from the chaff.
Get to know the various posters, their age, qualifications, education, etc.
We have some very well-educated members here -- and well-educated about the Faith in particular. We have older and/or wiser members, college educated, professionals, successful business owners, members with partial seminary training, members familiar with the Eastern Rite, members from all over the world, some from large cities as well as rural areas, etc. Quite a wide variety.
Also you can tell when one "dummy" gives bad advice, because it usually gets contradicted by most of the other members.
When 1 or 2 hotheaded young guys are on one side, and most members (on a forum like CI made up of serious Catholics) is on the other side, I think you can all guess which side it's safest to go with!