The problem with resercons

The Other McCain explains why Brooks, Frum, et. al. do more harm than good:

Some of my friends mistake my frequent criticism of "centrists" like Brooks et al. as a call to "purge the RINOs." I don't go in for that urge-to-purge stuff, and understand that ideological purity tests are a losing approach to pragmatic coalition politics.

The problem, rather, is when "centrists" (a word whose meaning is sufficiently nebulous as to require the scare-quotes) criticize conservatives in terms that undermine morale on the Right by suggesting that conservatism is not a viable alternative to liberalism.