If revenue was the sole focus, then you might expect it to impact usability. If it did then you would expect to see a higher bounce rate, as more people leave as soon as they visit your site. Or it could that mean you would see people spending less time on your site.
Revenue is just one of the factors Ezoic uses, to determine ad placement. Time on site, page views per visit and bounce rate are also taken into account. Which is why you are likely to see an increase in revenue, without it impacting user experience metrics. In a lot of cases they actually improve.
Example: Earnings due to automatic ad positioning
As you can see, the revenue has climbed higher and higher each month because of the automatic ad placements. But how did that impact usability?