I'm not sure I buy Ross Douthat's assessment of Charlie Crist specifically, but I think there is a valid distinction between purging careerist hacks like Arlen Specter (and possibly Dede Scozzafava, who was pretty clearly handpicked by the state's party establishment, even if they assessed her electoral prospcets in a 2-way election correctly) while letting the GOP provide space for candidates that don't hew to the Tea Party line like Mark Kirk and Scott Brown. In some cases, such as Kirk, the candidates have had to swing way to the right in order to win the primary, but still, I'll grant the premise. It's an interesting point. On this side of the aisle, Jim Webb's built up an incredibly moderate record, but no one complains about him the way they complain about Ben Nelson or Evan Bayh.
As for Crist, it's hard for me to look at Southern Republican who decides to restore voting rights to felons who've served their time and say he did so for crassly political reasons. Douthat and I almost certainly disagree on the function of stimulus spending, so what he sees as craven politics I see as good economics. The ed reform bill is a mixed bag, but even if we call the veto a bad move, Crist is two-for-three in terms of issues that have managed crossed my radar.
Update: the snarky version of this post was going to be titled "Grand New Partyism cannot fail, it can only be failed". But of course Douthat points to the purge of Bob Bennett (R-UT), who's primordial sin was to negotiate with wonky Democrat Ron Wyden (D-OR) to produce a wonky left-right health care plan that phased out employer sponsored insurance and replaced it with a system of predominantly private individual insurance. For this, there is a very good chance he will lose his seat in a primary.