You are correct that working on underlying issues is very important, but there is a huge practical value to blocking out distractions. First of all, it gets you started on scrolling a lot less immediately. Secondly, it makes concentrating on the important parts of life and thus the underlying issues much easier as you have more time and energy now. Thirdly, you will always have some bad days, you will always have some issues in your life that you can't fix (yet), but having a mechanism that stops you from re-entering the habit independently of your current state is really helpful in stabilizing your behavior.

What I'm trying to say is that blocking and working on the "deeper" issues are stronger when used synergistically, it doesn't have to be an either or.