I am familiar with those arguments Dave, but generally an opinion not based on any actual knowledge is not worthy of consideration.

"be ready to be challenged to support your opinion, to demonstrate that
you are not prejudiced, bigoted or otherwise unduly partial. Even if
you're not challenged, you should be honest enough to offer that
support in any case. That would mark you out as a person of integrity,
not a mere charlatan."

"It seems to me, that "discussions" that consist solely of unsupported opinions, don't go very far. There has to be some sort of rational basis to a discussion "

"However, when a speaker or writer expressly or impliedly calls on other individuals or society in general to believe and/or act on an opinion he expresses or endorses, there is a burden placed on him to at least attempt to substantiate the opinion. In the absence of substantiation, there are results that follow. Some of them are:

1. Hearers/readers are likely to discount the opinion out of hand.
2. Hearers/readers are at least tempted to reject other opinions put forward by what I'll call the initial opinion-expresser, even if an explanation is attempted in that case.
3. Such blanket rejection might be applied to others who echo or support the unsubstantiated opinion, unless they supply the missing rational basis or at least attempt to do so."