Actually, I found an experiment that directly contradicts your statement. So my disagreement is IMHO valid and your appeal to "mountains of telemetry" is not. To me it seems that you've just parroted the chorus without trying to understand the problem by decomposing it into pieces and trying to attribute the potential causes. Which just happens to be something that I spent some time doing (total amateur hour and N=1 but sort of worked for my purposes).

https://www.slideshare.net/slideshow/design-for-continuous-e... - look for the slide 32.

Etsy ran A/B tests with and without endless scrolling. Same content source. Infinite scroll haven't produced any increased engagement: surprisingly, it decreased it - people searched less. Potential reason: it was a store, not a social media feed, the feed wasn't addictive in its nature (decreased relevancy, lower chances of finding something good buried down further and further) and the whole alternative pagination design didn't help at all. This is my interpretation, but c'mon - if you're appealing to the telemetry: here's the telemetry, how'd you explain it?

In the neighboring comment, I was mistaken in that it would still increase length of browsing a bit, turns out it was off-putting.