What restrictions? You mean the ones that the OPC website AGREES with?
Protestant churches are growing while the RCC is contracting.
Which ones? Do you mean the ones that have dropped other "loony restrictions"? Like the "loony restrictions" against female clergy, homosexuality and abortion?
You posted it but perhaps you didn't read it. I suggest you do so.
In case you didn't read the paragraphs you posted, I'll supply one of them for your understanding...
In the end, God doesn't give a pat answer about contraception. But he does provide a framework within which believers are responsible and free to make godly decisions. In fact, this framework does condemn most of the world's approach to contraception—but not because it's contraception. Rather, it condemns its fundamental self-centeredness (Ps. 10:4). Believing couples should soberly examine themselves as to whether they conform to this worldly selfishness and, if so, repent. Still, the biblical principles which we've considered seem to imply that—given right motives—God does permit contraception.
Hopefully you have now read these few words from the OPC to comprehend the simple fact that much of the world's contraception is based on "self-centeredness" (no doubt alluding to the world-wide use of abortion as a contraceptive.)
In case you're still not getting it, I'll repeat the last four words on the subject from the Orthodox Presbyterian Church which YOU posted...
"GOD DOES PERMIT CONTRACEPTION."
The Italian cheese stands alone.