Perhaps not relevant to LinkedIn specifically, but in general people install these apps because they eventually get fed up with the purposefully crippled mobile website badgering them about it. Ever tried to use Yelp or Reddit's mobile websites? Impossible.
If you don't mind seeing the desktop interface, prepend "old" to the domain on any reddit page (i.e. change the domain to old.reddit.com) to bring up the legacy interface. Loads quick and works fine on mobile if you don't mind zooming.
That said, it's ridiculous that this is necessary.
Actually, no, I never have. But if I wanted to wallow in these sewers for some reason, and the mobile sites were unusable, I would use my laptop, or just manage to find some way to survive without them. Installing their apps is out of the question.