The big man upstairs let me flounder around for years and wallow in the consequences of my choices until the light finally went on. I feel others deserve the freedom to hopefully one day find the grace I received. I dont know why so many people that enter into the belief system you mentioned feel they have the right (or obligation) to dictate to others how they should live. As for me, I've always been far too consumed, struggling to deal with all the planks in my eyes, to find time to try to tell others how they should live.
Reading your post reminded me of an argument I make to those who say we shouldn't judge (as if we should never make judgments about anything, which is not what the teaching suggests).
There's a difference between perfection and responsibility.
Perfection says we can't do anything or correct any wrong unless we are totally free of wrong ourselves. Of course, this is impractical because then we wouldn't be able to correct anyone. And, of course, society would collapse.
But responsibility says even though I am imperfect, I have a responsibility to my family, my friends, my community, etc. to continue to work for what is good and what is best for my family, friends, community, etc.
So, let's say I'm an imperfect parent and I have things I have to work on. I still have the
responsibility to teach my kids what is right and wrong, how to be good citizens, etc. I can't say, "Well, because I'm not perfect, then I can't instruct anyone else." No, such a response is irresponsible.
Now to answer your question, the reason why so many people with a belief system similar to mine take the position that they do is because, ultimately, the decisions that people outside our belief system will impact us, and that negatively. I tell people, "Okay, I will stop forcing my beliefs and views on you if you can promise me that your actions will
ONLY impact you and that I won't in any way be dragged into helping solve problem created by you and those who believe as you do. So that means none of my tax money goes towards finding cures or funding programs that help solve problems you've created for society. If you can promise me that, I'll stop forcing my views and beliefs on you."
Of course, they can't make that promise. And neither will I stop trying to shape society to reflect what I believe.
Many on your side see just
your personal rights. You don't see the
consequences your actions will have on yourself, your family, your friends, your community and society in general.
Now, there's a balance we have to maintain, sure. But we're talking about policy issues, and all taxpayers and citizens have a right to shape policy.