Correct. Where "high quality" is pegged to apps like Tweetbot or Instagram, it's not currently possible to make webkit-based apps that are equally performant.
Even examples of "web with native wrapper" apps, like Facebook and OkCupid, are dramatically, dramatically worse than best of breed native apps.
Interesting that your two examples of "high quality" apps don't have web counterparts. Both Tweetbot and Instagram exist solely as native applications - which means that it makes business sense for them to develop natively.
Companies like OkCupid and LinkedIn, whose apps both rely heavily on web views, need to think about the benefits of using the same code across multiple platforms. I'd tend to argue that both of those apps are pretty well-done. They certainly lack some of the really slick transitions and polish of an app like Tweetbot, but I definitely don't think either one feels cheap.
No offense, but Facebook's webapp is stellar compared to the native app, Instagram can't stop crashing left and right and I don't even follow anyone, Twitter's app has taken it ages to get where it is today.
Even examples of "web with native wrapper" apps, like Facebook and OkCupid, are dramatically, dramatically worse than best of breed native apps.