This article mentions two things as if they are unrelated. That the cellular environment is crowded is exactly why you need transport proteins and vesicles. All

This article mentions two things as if they are unrelated. That the cellular environment is crowded is exactly why you need transport proteins and vesicles. All the really fast proteins are mostly going nowhere, they're just wobbling on the spot bumping into everything crammed next to them. Sandwiched most of the time between membranes they cant diffuse through freely. Its like angry jelly not hot soup.