It’s a psychological trick used both by hostage negotiators and con men alike to build trust and inclusitivity, and to maintain engagement of the other person in what otherwise might be a confrontational exchange where the other party would be motivated to disengage. It exploits people’s tendency to try to meet kindness with kindness.
People generally respond positively to hearing their name, and will sort of pay attention for the next few seconds to hear why they are being addressed. In a “selling it” context, using their name frequently keeps the other person engaged by making them feel involved in a conversation that might be entirely one-sided, or where their contributions are being minimized, dismissed, or rebuked. It also builds comradery through familiarity. If you are taking time to use their name and to include them, then you become a bit less threatening and perhaps even more familiar to them. Over time, it can wear down predispositions and make people reconsider that r commitment to their own goals.
Yes, it’s just as insidious as it sounds, and is a technique used by gaslighters, con men, and other abusers as much as it is by sales people, crisis negotiators and politicians. Pretty much anyone who needs to soften your opinion of their position would use it to try to draw you in and keep working on you might use it.
The only real defense is to spot it being used on you, and to assertively disengage.