Relevance of expertise

There is a common argument that because the Bitcoin Core developers have the most extensive technical expertise in Bitcoin, we should give their opinion on any Bitcoin-related topic more weight than we give to anyone else's opinion.

To draw this conclusion in general would be incorrect. Whether this is justified depends on whether the disagreement in question hinges on the subject that the Core developers have the most expertise in.

Imagine Core developers and a group of industry wallet developers disagree about an issue, and that topics X, Y, and Z all inform their views on the issue. Assume Core developers are the world’s best experts on topic X, but just one of many groups with valuable insights on topics Y and Z. Assume the group of industry wallet developers agree completely with Core on topic X, but disagree with them on topics Y and Z. Suppose this group of industry developers has equal expertise in topics Y and Z as the Core developers. In this case, favoring the position of Core developers in this disagreement because of their expertise on X would be unjustified.

Note that favoring Core's position is unjustified in the above scenario despite the fact that topic X is relevant to the issue being debated. What matters is whether the disagreement is about X, not whether X is relevant to the disagreed about thing.