In my 50 years of riding, I've found that there are several ways to mitigate the problem: good fit, expensive shorts ($100 or so), change position often (especially some stand up time), good saddle, chamois butter and take a break once in a while to enjoy other forms of exercise.
One half inch, one way on another, up or down, forward or back, and a few degrees of tilt can make a huge difference. Get the fit right first, but don't be afraid to tinker with it. Things change over time. You can gain/lose weight or become more flexible. You can spend all kinds of time and money trying to find the perfect saddle. Just as a Brooks has a break in time, so does your butt.
...or try a recumbent.
Bike fit, riding position, and time in the saddle are the answers. Going to a recumbent should not be required. If you want one fine, but don't let the bent riders convince you it is the only way.
I just don't get the resistance to a recumbent. No, it's not the "only way", but after years of trying the tinkering, adjusting, and "time in the saddle" that the above members suggested I tried a recumbent and all the pains disappeared. And it wasn't just the "groin/butt" pain that went away. So did the wrist pain and the neck pain. On a recumbent you are sitting in the same position as in a chair or in a car. Your body is aimed at things ahead of you, not at the ground. Yes, there are many types of recumbents (long wheel base, short wheel base, high racer, low racer, delta trikes, tadpole trikes, etc.) Maybe someone like staehpj1
tried a style of recumbent once that didn't suit his/her style. To me they are the ultimate touring bike, to others maybe not.
I can sort of understand the resistance to recumbents from the under 30, got to look cool, racer crowd that reads Bicycling magazine, but I don't get the resistance from long distance riders on this site. Many people abandon bicycle riding due to the pain. My opinion is that many would continue riding if they tried a recumbent style.
Adventure Cycling's current campaign motto is: HELP US INSPIRE OTHERS TO TRAVEL BY BICYCLE. Encouraging folks to find the "perfect fit" to make a diamond frame/upright style bike more comfortable may work for some. Others may be inspired to ride with something like a recumbent style bike.