Nothing in that doctrine calls for more wheat than tares, and when speaking of the narrow gate, the Lord said Few there be that find it.
Usually Calvinists are the ones charged with exclusivity. 8~)
In Matthew 7 Christ is cautioning us about the rigors of the Christian life. But there have been billions of Christians who have been given faith in Christ. That's more than a "few," so Christ must not be speaking of quantity as much as quality.
After all, it's a wheat field, not a tare field.