TBH, "Don't trust anything on Wikipedia" was always just stuck up posturing. Plenty of badly sourced, badly edited and biased articles in regular encyclopedias too, but because Wikipedia is contributed to by the unwashed masses, don't trust it.

"Don't use Wiki as a primary source" is much more to the point - it's not meant to be. Use it to find the primaries.

Also, I don't see this as "reducing breadth" so much as attempting to hold to a minimum standard of "has this been written up anywhere by someone other than the people who started it?" which isn't perfect, but it's been the stance since the beginning.