RSS isn’t really a privacy technology. It’s just a way to keep up-to-date with content published on the Web. Like you say, to avoid having to remember to check each site and go to each site individually. However, there are less private ways of doing the same thing (social media platforms), so in that sense it might be a more private option.
I can think of a couple of privacy downsides to running a feed reader on your laptop or phone. Information about the times of day your machine is running and checking for feed updates will be leaked to the sites whose feeds you subscribe to. Information about what sites you subscribe to will be leaked to the network your machine is connected to when it checks for feed updates, because the network will see the requests going out to those sites.
if you use RSS for YouTube, the main benefit I can think of is that you can use RSS to ‘subscribe’ to a channel and be notified when it releases a video without logging in or even having an account. Also, normally every video a channel releases will show up in your feed reader, whereas if you subscribe to a channel in the normal way, “The Algorithm™” won’t necessarily show you every video the channel releases. It can also be used to catch videos that become unlisted after initially being made public for a short period. As @ramnasko said, YouTube will still get your IP address, or the IP address of your feed reader host, and it will still see if you’ve watched a video.