It wasn't meant to be rude and dismissive, but to point out the very real fact that young people at their age generally have a much stronger desire for monogamy than they are most likely to feel at, say, my age. If you think about it -- and most people won't -- there could be evolutionary reasons why that's so.
No doubt you have convinced yourself that you currently know, at 26, what you will want at, say, 60. Personally, I have discovered that I myself was a fool in my 20s to think I knew what I'd be like in my 50s. But maybe you'll prove different.