Also, H1B began in the 90s.
But there is the risk people might game the system to take advantage of that framework (though that sounds like a higher hurdle than the H1B charade now).
There isn’t an easy answer but for sure what exists now isn’t working.
OPT is mostly only useful to give you extra tries on the H-1B, since the current system is a lottery. Since that lottery is once a year, OPT also makes it easier for employers to hire you at any given time so that you can wait for the next lottery. But no employer is hiring an OPT with an expectation that they will leave in 1 or 3 years, so the H-1B is still what everyone anchors on.
There's basically no way to get a green card straight after an OPT. There's also no way to extend an H-1B past it's 3+3 years.