Aren’t those segments deals between the creator and the sponsors and nothing to do with Youtube?

Indeed. But they typically are contingent on a certain number of views. If adblockers cause that stat to go down, then you get the opposite of what you are aiming to achieve: the user will see the "message from our sponsor" but their view does bot contribute to providing that sponsor with the data that the youtuber held up their end of the deal. Ends up bring an unpaid ad.

	▲	Wurdan 4 days ago \| parent \| next [-]
		Views might be important to get the attention of a potential advertising partner, but once the relationship has started then keeping it going will likely be dependent on much more relevant metrics for the advertiser. And those metrics will usually be tracked on their end, rather than via YouTube. I'm referring to metrics like click-through rate, propensity to order, revenue on advertising spend, etc. Personalized referral URLs and discount codes are what allow the advertisers to connect their tracking and reporting to the originating YouTuber.
	▲	aurareturn 4 days ago \| parent \| prev [-]
		Ok but Youtube shouldn't payout.

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twothreeone 4 days ago | parent | prev [-]

yeah, FWIU they are an increasingly popular monetization channel in addition to YT's built-in ad-rev system (which is famously very bad for creators)

*) and conveniently for YT that out-of-band monetization channel - which they don't profit from - is the exact thing that's negatively affected by an overall drop in view counts