Anyone who thinks that circuмstances don't matter, just consider that there is a huge difference between
A) an engaged couple acting as though they were married, on the day before their wedding.
B) a newlywed couple, married earlier that day, acting as though they were married.
Same behavior, only 1 day apart. But A) leads to an eternity in Hell, while B) is not even venially sinful. The devil really is in the details!
Just like in ancient times, you could have more or less "naturally virtuous" pagans, whereas today paganism is much more vicious, being an explicit rejection of Christ and His Gospel. You can't have "I didn't know any better; I was doing my best in the pagan darkness to be virtuous"
That's why today's POST-CHRISTIAN society is so much worse than your typical pagan society. It contains an implicit malice, being a rejection of Christ Who has already come and given us His law.
Likewise, Archbishop Lefebvre giving it one, last, Boy Scout try, to appeal to the Pope to allow the SSPX free reign, etc. was admirable. He didn't have our hindsight of Rome's behavior 1981 - 2015. But after the malice of Modern Rome became clear, and the depths to which they had sunk, +ABL's tune changed accordingly. He consecrated 4 bishops without Papal mandate in 1988, and his tune from then on until his death in 1991 was something along the lines of: "beware! DO NOT make a practical deal with Rome, whatever you do. We will have to wait until they convert."