Sponsors might ask for some of the creator's analytics, eg. raid: shadow legends probably isn't going to sponsor channels that have very low mobile viewership compared to desktop. There are also paid analytics tools, eg. VidIQ, which can make good guesses about some metrics.

I don't believe the view counter gets incremented when using any unofficial front-end/downloader.

How would Google's backend know whether the traffic comes from their own frontend vs a utility like youtube-dl (assume for the sake of argument that the utility is trying to make the traffic look like normal YouTube traffic)?

Youtube proper does a lot of JS, eg. a view is usually only counted after ~30 seconds[0] and does other things like logging the current timecode so that it can return to that time in case the user clicks off the video and returns to it later[1].

0: https://www.tubics.com/blog/what-counts-as-a-view-on-youtube....

1: https://i.judge.sh/rare/Cherry/chrome_H0p9bAoLgy.png the red line is how far in i've watched.

If the actual video URL is somehow grabbable from the API you might miss whatever triggers a +1 view from the website in theory

It does, it shows up as a "Other YouTube features" for the source.

Though, YouTube seems to do some aggressive deduping here, if I download from 5 different IPs, excluding the IP I'm logged into YouTube's services, I see 5 views. If I download 50 times from one IP, I see one view.

Good to know, thanks for the correction!