The game feels great to play solo and gets progressively more frustrating when adding players
The shared loot adds too much downtime. Runs are already bordering on lasting too long for a casual session and the regular pausing for loot deliberation does not help that. It's ultimately just added friction that works against the brisk pace that the game is trying to encourage.
Solo, upgrades pop up immediately and the player is quickly on their way to the next encounter. In a group, wrangling players brings the momentum to a screeching halt that is further extended by the need to coordinate perks and select one by one.
It's a system that ranges from slightly annoying with friends and while potentially making the game borderline unplayable with randoms, all while being completely unnecessary as the game functions perfectly fine when solo.
This is the type of thing I'd expect out of a challenge mutator like limited oxygen in DRG. As a core mechanic it just serves to extend an already long play session.