Conservatives do, by looking at people with less-conservative views and deciding if they like the outcomes or not.
So, for example, people who are Wenger's, or Hoovers, or whoever, might look at (for example) people in BMA or LMC or Charity and go, "Hmm, that's not an outcome I want", and will view things from BMA and LMC and Charity people - and their ideas and opinions - with suspicion.
Unfortunately, the conduct of less-conservative people has pretty much enshrined vaccine scepticism into the conservative position (I would support this personally with regard to stem cells, but don't support overall vaccine scepticism). However, the conduct of less-conservative people is one of complete contempt to conservatives on this topic, so they don't do anything to build up credibility for themselves.
This applies to many other areas. For example, BMA people are not viewed as credible when it comes to opinions on consuming media since their young people have a reputation for watching questionable movies. (Don't shoot the messenger - I'm just sharing with you what I hear from other, more conservative people.) My own group is viewed with suspicion by other groups when it comes to clothing because we are less conservative in areas of dress.
The title of "how to challenge conservative superiority" may answer the entire question without meaning to. Why would any conservative Anabaptist person want to listen to the opinions of someone whose agenda is "how to challenge conservative superiority"?