> We always have to support HTML5 because so much of our traffic comes from email. When we were [serving] a smaller group [of users], we were hoping we could duplicate all that mobile web work to make our clients faster in terms of code deploys.
This has been my experience as well. When you click on a link in an email, the LinkedIn site would take you to the login screen. This screen is so heavy that it takes an inordinate time to even render!
Clearly, they have tried to cramp in too much into their mobile experience. They should not duplicate the entire functionality but rather simplify it considering the smaller form factor. Building a much lighter version of their site would be the right direction for them, rather than building native apps.