I don't think that's remotely true if you keep the responsive web app simple. YNGNI and KISS and what not. I've been doing this for over ten years. In that time I've seen large web applications built for under 4k; I've also seen massively overbuilt simple applications go for 50k+. It comes down to often how needlessly complex you make the stack. If you stick with solid simple guaranteed tech instead of cutting edge y…
I think the author is already addressing this: Yes, you can build 2007 websites much better now. They will be consistent across platforms and perform great. But my 12 year olds don’t want 2007 websites. They want 2016 apps.
Just a simple example: it's trivially easy to make large, flat shaded buttons on the web. That's going to be more familiar to younger users than native web buttons like those on HN.
However, there's also spending weeks to make a web button that animates smoothly from one container to another and has a SVG icon that morphs into another different icon with magic sparkles. Doing that on the web will require grossly perverting the DOM and all of the web interaction expectations.
A lot of the things we consider "Just 2016 App Things" are performances that native app builders have to do to give clients a reason to believe their $300/hour is well spent. No real value is produced except "design" awards for the shelf.