

Yes, a lot of feeds, especially the more commercial ones, only have a teaser in the feed. Most people don’t like this. But lots of feeds want to try and estimate how many readers they have. Since RSS has better privacy by design they can’t really tell if you read it or not. So they force you to visit the site.
However IMHO RSS is still valuable here. Because now I get my notifications in the same place. For example I subscribe to YouTube via RSS even though YouTube tries as hard as it can to force you to watch the video on-site or in-app. This is because RSS lets me reliably get notified about all of the channels and playlists that I am interested in. I can also mix in feeds from elsewhere (Nebula, PeerTube, …) into the same feed so that I just look at one place and have all of my video history.
In some cases you can combat this. Many feed readers will attempt to scrape the full article from the site. This means that you may not have to leave your reader to enjoy the whole article. However this isn’t very reliable and can be pretty difficult depending on how antagonistic the site is. There are also tools that will consume the original feel and produce a new feed with (hopefully) full text articles.
But at the end of the day this is the choice the site is offering you. If you don’t find their feeds useful just don’t use them. You can either visit manually to check, use whatever other notification systems they provide or try to build your own feed (see “feed builder” tools that scrape sites to produce feeds).
No I just use YouTube’s feeds.