Comment by mrandish

> the advertiser is the customer.

Excellent point. If any change on the site caused ad views or clicks to drop by >1%, automated tests probably shoot flares up to the exec level. Whereas the vast majority of users on FF are blocking ads anyway, so their lagging performance probably barely registers on those tests.

While YT probably still has non-ad automated performance tests, in the case of a non-Chrome, non-Apple desktop browser, those tests probably run every odd Thursday and regressions send a toast message to an intern. :-)