Mark must know that it is the little Republican primary voters who keep the establishment entrenched in election after election.
The ones that the GOP-e insist on keeping "open"?
That's more easily said than explained. Primary turnouts are fractions of the general election turnout of voters, but as far as most of the House of Representatives goes, if you win the primary, you probably got the job. Why would a conservative or small 'l' libertarian vote for someone on the right in the House, and then vote for a RINO for statewide office or President? That doesn't make sense to me.
I've posted results from exit polls since 2006. You can find them using 20xxexitpoll as the keyword by substituting the correct numbers for the particular general election.
2006 and 2008 GOP general election losses were explained by moderates and/or independents bailing out on the GOP.
In 2010 the GOP got 60 % of the white vote for the first time.
In 2012 the GOP got 60 % of the white vote, but an expected 7 - 8 million white voters didn't go to the polls.
Open primaries in some states only explains part of these anomalous results. Low information independent voters in the general election explains more, IMHO. There are many states where the independents, aka unaffiliated, outnumber registered rats or pubbies. IIRC, the national average of those independents is close to 40 %.