Absolutely. The only reason it would be false is if:

- Google cared more about search quality than their ad business

- This kind of self-dealing were illegal, easily-prosecuted, and heavily fined

- Google were an ethical company

We know that all three of these are false, so we should assume Google is self-dealing. We've caught them (and every other large tech firm) doing it repeatedly.

I do know a great deal of sites that rank higher without ads compared to compeditors that do have ads ... but anecdotes are worthless and the only one who can answer are the people at google search.

Is this in response to the recent leak?

Does https://ads.google.com/intl/en_us/home/campaigns/search-ads/ answer your question?