It can. From what I've read, if people watched the whole video and gave it a thumbs down, YT will still consider that it held your attention and it won't have much of a negative impact. But I do believe the less time watched and the more thumbs down a video has, the less likely YT is to recommend that channel to viewers of similar content.
The ratio could make any companies they might reach out to for sponsorships apprehensive to work with them, and it will also scare away other vloggers from wanting to collab with them. Notice even their "good friends" the Brickster & Dylan have been decidedly quiet about the drama this last week, instead of coming to their pals defense.
Then there's the only thing that matters to BLAB....their egos. They can try to spin it and say, "hey, you're still watching". But most likely people aren't. They're just seeing the name and clicking the thumbs down and moving on.