I would kinda disagree with this, but thinking about it I guess what would be considered "vulnerable" or a "true connection" depends on the character and readers. Given that vulnerability can technically mean anything from opening up emotionally, to showing affection, or having sex. This also goes for a "true connection" in a relationship, seeing as some people are less or more sexual than others, so it all depends on the type of character you create. Some people would find the simple act of showing affection to someone a bigger deal than sleeping with them, if they're the type to sleep around but don't know how to have a meaningful relationship.
Personally I don't think sex scenes are necessary unless it's mindless porn, but I can't relate to that since I find sex to be superficial. So really, I'm not the target audience. I suppose it's just as important as any other way of showing vulnerability and connection though, since people experience those things differently, and there's no one way of representing it. I'm just sick of seeing it as the ultimatum to a "healthy relationship".
-vents butthurt as I draw a comic with sex in it-
Oh yeah! I'm totally not trying to tell people what to do with their work, I 100% support freedom to create what you want. This is more of an analysis thing, mixed with bitching about the over-saturation of sex=love in media.