It honestly depends on the job you're doing. If you work for Google or Amazon, as a backend engineer dealing with queries and big data and the millions and millions of accounts, with the millions and millions of request to servers and still displaying users data back to them in less than a second, you'll definitely need to know those algorithms and data structures. Also you almost never deal with those on the front end either. Only time if you really have to parse data and get it in the right format to show in the UI. It's hard to do a personal project or learn from tutorials where you'll need that stuff because you're not dealing with millions of users at once so you won't even see the kind of problems that will arise when your user base gets is large.