They already do, go use the latest version of yt-dlp to download like 20 videos from a channel without passing cookies, and a very short time afterwards, everything at your IP address will be blocked from watching any videos unless you sign in.
I download a lot of things from youtube using yt-dlp. So far I never had any issues with getting ip-blocked. In contrast, Instagram ip-blocks me very fast when I use gallery-dl to download a profile. I usually turn my modem on and off to get a new ip address.
