So its very clear that using a framework to build up your website is an important thing, you can save a lot of time and energy by using one like Laravel or code igniter 3, but there's one thing that web developers beginners should understand and its the MVC architecture and how does it work, and in order to understand it you should build your own MVC framework, so when you use another advanced framework you know what you are doing and you know the role of the controller, the model and the view and why they exist, sure you can read about that but there's nothing better than learning by practice, back to 2015 when I first created my first own MVC framework, I gain a lot of experience and my php skills dramatically improved.
The reason beginners get stuck to understand frameworks and take a long time to learn the basics is that they don't really understand the MVC architecture, once you get used with it, everything becomes easy.
Here are the things I learnt by that:
I learnt how to create a validation system.
How does routing work.
I knew about .htaccess.
I learnt how to use PDO.
I built a query builder which made my code very organized and easy to read.
I created a views system with basic PHP and HTML templating.
I learnt about flashing error messages using session.
So now when ever I use a framework I know what I'm doing when writing code, and in final its a was great learning curve, I advice every beginner to take the experience and put some efforts to do so, YouTube is full of courses you just need determination.