Brand management people, who normally handled this, cost money. Self-service brand management with LLMs costs less money. Building this in as first-party product commoditizes this, costing the vlogger even less, while YouTube gets to keep them in-house and focused on the platform, instead of external services that may be cross-platform.
Yes, so if we assume that cost saving is the only metric that is meaningful and that there should be no legislation or norms saying otherwise, then indeed it follows as a consequence.
Cost saving is basically what drives the market, and thus shapes our entire reality. It's not some side goal of some people, that you could suppress or eliminate - it's the thing itself.
As such, I'm not sure where you'd like to draw the line. There's no obvious, defensible place to do it, not unless you're willing to go back up, expand the scope and fight the entire advertising industry on principle - in which case, I'll agree, because I believe that's where the problem originates and where it needs to be solved.