I don't have LinkedIn installed, but it's hardly the only app guilty of this. My phone has probably a dozen apps or so that take up much more space than I would expect (400 MB for the iRobot app that runs my Roomba? 250 MB for Firefox Focus which is now the same size as 'full' Firefox?)

For many of these apps, I use them frequently enough that the space tradeoff is not a concern.

For many others though, they're in that awkward middle zone where I use them once every month or two. But because the apps are so large, I don't want to have to waste a quarter gig of data to download them on the fly, so instead I keep them on my phone. And collectively they take up 5-10 GB of space.