One-issue voters may call themselves conservatives, but they're really just one-issue voters. They are useful to conservatives when they happen to cast a vote for a candidate who holds other conservative views, but they are not reliable voters.
Mostly they go around threatening to withhold their votes, especially concentrating on candidates who'd they'd never vote for anyway.
Your rant against the mythical 'one-issue' voter is a very old and very tiresome pro-abortion smear tactic, and marks you as someone who is hostile to pro-lifers.
Why do you despise folks who despise abortion?