The conditioning of human opinion is not an entirely unknown phenomenon in history. Our convictions and beliefs are heavily influenced by those we perceive to be moral figures of authority - parents, politicians, pastors, and so forth. If they shout a "moral truth" enough times, it will become our reality, dictating our actions and behaviors. Pro-Palestinians, such as Hasan, have become popular political pundits because of this rhetoric. After attracting an audience of normies, they will repeat values and beliefs until their audience wholly adopts them, thereby rejecting new perspectives or nuance.
Though their power permeates throughout Twitch and other streaming sites, these political streamers are merely cogs in a machine, replaceable and unimportant in the long-term. As long as there are socialists, there will be popular figures who behave almost exactly like Hasan, and propaganda will remain an effective tool for manipulation. Manipulation and propaganda will continue to exist as long as there is politics; we cannot change this.