I'm really tired of everyone talking in absolutes (also the overuse of the word terrible). The right answer is (almost) always "it depends".
It depends how critical that functionality is to the core value the site provides. It depends how appropriate it is to a mobile platform experience.
As a contrived example I'd probably be perfectly happy if I could only browse, read, and maybe vote on HN if the mobile experience of reading was significantly improved. I never want to write a comment from my phone, I hate typing on it. Not a great example since a textarea isn't complex and it's easy to add to a mobile layout, I just want to get across the point that not all interaction is appropriate or important on every platform.
This is why responsive design is hard, because doing it well means far more than just changing the layout, size and visibility of elements. It is a different interaction paradigm and generally will need to be treated as such to maintain a quality experience.
>As a contrived example I'd probably be perfectly happy if I could only browse, read, and maybe vote on HN if the mobile experience of reading was significantly improved. I never want to write a comment from my phone, I hate typing on it. Not a great example since a textarea isn't complex and it's easy to add to a mobile layout, I just want to get across the point that not all interaction is appropriate or important on every platform.
But you didn't get across the point, because your example isn't true. I want to post on HN from my phone; heck, I've posted on HN from my kindle before. I wouldn't give that up for all the optimized mobile design in the world.
Grandparent is right, an absolute is appropriate here. Provide all the functionality of your desktop site, or I won't use your mobile site.
It depends how critical that functionality is to the core value the site provides. It depends how appropriate it is to a mobile platform experience.
As a contrived example I'd probably be perfectly happy if I could only browse, read, and maybe vote on HN if the mobile experience of reading was significantly improved. I never want to write a comment from my phone, I hate typing on it. Not a great example since a textarea isn't complex and it's easy to add to a mobile layout, I just want to get across the point that not all interaction is appropriate or important on every platform.
This is why responsive design is hard, because doing it well means far more than just changing the layout, size and visibility of elements. It is a different interaction paradigm and generally will need to be treated as such to maintain a quality experience.