Some reflexions on this, purely independent personal thinking. No statistical data to support these statements.
1. The rule in overall (if assumed to be correct) was not directed to any specific gender. What was power relations between men/women in congregations those days, do not know.
2. Today, at least in places I've visited women are strong, I emphasise, strong majority of witnesses. Thus negative effects of this rule will mostly hit women, by default. Unless one man could have multiple spouses the ratio 2:1, 3:1 etc. will just make it statistically impossible to get it right.
3. For relationbuilding, men are not that eager in most cases. If allowed they are more interested in dipping the sausage in many ponds.
4. Getting older, without having a children around, may not be such problem to a manly man than to a women. Mostly due emotional reasons, but even due some physical limits for having kids, age that is. For men please refer to point 3. and note that they can be fruitful until they die. (even after, if some freezing things have been done).
Yes looking at this day's congregation it seems cruel, as in my opinion women seek for steady relationship and want to have own children, more so than those few men around. But the background when this rule/guidance was written might very well have been totally different, therefore the law as such might not been meant to be difficult to follow. So the question really is how it is implemented today. Funny enough this is not DF offense, even the mixing-relation is very visible in the community. Yes, you will loose your wonderful privileges, the same applies those openly supporting your relation, but it is not DF thing. Some sensibility is obviously around, but is it sensible enough is of course debatable.
CP