Oh, I read the article. Twice.
I'm 40. I have a 17-year old daughter. Would I want my daughter to date a significantly older man once she's of age? No, but that's my generalized opinion, and I might want to look into the situation first, if it were to arise.
In simple terms, I personally don't think a 19-year old should have a relationship with a 40-year old (it goes both ways, by the way). However, 18 is the age of majority. If a 19-year old and a 40-year old are interested in dating, then they're both adults and that's something we can leave both persons to explore. So while I do share that opinion with you, I don't agree with it being so generalized across-the-board.
Let's not generalize that all older men have bad intentions and use seniority for power, which is one of the things your article warns against. That's a slippery slope. That also leads to a potential generalization that younger women who are interested in older men also have less than noble intentions in dating them (there seems to be a lot of media around the "sugar baby" phenomenon even here on Medium for instance).
You mentioned dating in your comment. Maybe we need to qualify the level of the relationship. I'm in touch with a lot of other people in my age group (mostly dads, mostly single dads like myself). None are interested in pursuing relationships with people half our age. But some have encountered younger women interested in them--such as coworkers who are even as young as 18. They open to dating, just to see if there is any merit to pursuing the relationship further.