In practice, "free YouTube views" come from two fundamentally distinct sources:
Websites that operate on a "you watch mine, I’ll watch yours" basis (Sub4Sub) are equally detrimental. While these are technically "real" people, their intent is not to consume content but to earn credits for their own channel. These viewers rarely engage (like, comment, or subscribe) because they are incentivized only to let the video play while they look away. This destroys your Click-Through Rate (CTR) and Engagement metrics. To the algorithm, your video appears to be unpopular, preventing it from being recommended to genuine viewers.