Probably both. I remember the very first versions of Gitlab when it was just announced on habr.com, and it used to be a minimalistic (more in terms of UI) version of Github. As the functionality grew, things got a bit out of control.

Currently UI looks more like it's been designed by people who write code rather than those who have spent considerable time thinking through user interactions and designing based on that. So it's not bloated in terms of the code and libraries, but rather all of the functionality is just thrown to the user as is without much thought.