Do they need to be backed by evidence to be correct? What if they are just right? Do other companies not running Erlang mean its wrong? Because that's a bold argument that could be restated to disprove many things -- X technology claims to do Y well and has a track record of doing it really well, but Z companies don't use X technology, therefore...[insert whatever].

I don't believe in blindly believing things without evidence either, especially if I have never encountered them before, but I also don't believe in blindly dismissing experience of world renowned experts in their field because they didn't provide me a point by point prooftext of every claim they made (Again we aren't sitting here discussing a dissertation or mathematical proof). Their experience and what they've provided to the world is the evidence. We took this 19th century german ultra-materialist philosophy too far here in the west, and that's what gave us post modernism/poststructuralism with its disastrous consequences, but it still seems like we haven't learned anything from that.

The ancients had it right that theres different types of knowledge, and different ways of knowing things (and knowing them to be true, at least as far as it mattered). We here in the modern era with the most unfettered access to information have quite possibly the narrowest definition, ironically.