You are entitled to your opinions but how many poly people do you actually know? Or are you just making a value judgement based on your bias? 25-40% of supposedly monogamous couples are cheating on each other, so it's not like that's an inherently "better" system. The French are just more realistic about the fact that this is what people tend to do (if they don't have any other, more honest options).

I've been happily poly for close to 10 years and monogamous for 20 years before that (with the same partner) and know a lot of other people - many of them women - who find this a much more empowering, less patriarchal relationship style. Partners have to learn to communicate well, be responsible for their own emotions, negotiate, talk through and manage their insecurities, etc. These are skills everyone should have, no matter their relationship style, but mostly it's not something anyone bothers to learn, because they rely on the "structure" of monogamy to do the work for them and then it often doesn't work out so well. How many couples who are "faithful" are not happy, not having sex, not communicating? It's a HUGE number.

Not every poly person is doing their work, and not every relationship of that sort works out - but when people are showing up for that kind of lifestyle in the way that it's intended, it's very intimate, healthy, and there's a lot more transparent communication than the average supposedly monogamous relationship.