Granted, it's a lame Internet meme, but it got your attention, no? My argument rests in a single word: granularity. If you picked up on that, you need not read the rest of my post. For those of you who need one or two concrete cases, read on.
1) You may not need me to tell you that containment associations simply fail to replace Smallworld's internal worlds. Internal worlds allow an independent coordinate system, which I suppose requires a way to trace between feature datasets, and at this point I need say no more.
2) That aside, here's a nifty little diagnostic tool -- stolen from Smallworld -- that I implemented for the old geometric network, and I challenge Esri to allow me to duplicate it for the new utility network. This is how it works in ArcMap: you click a button, and it displays the actual edge connectivity for junction features in the current map view.
As far as I can tell, this functionality is not possible on a utility network via the Pro/REST/Enterprise APIs. You can access the ancient code here:
And I'll leave it to you kids to prove me wrong. To be fair, I did hear, from certain folks at the DevSummit, rumors of a ForwardStar-ish implementation to come, but hey guess what, it's not here yet. Hence my original point.