There are many reasons to learn WordPress but here are 3 good ones: speed, CMS knowledge, and one of the biggest is the job market.
You don’t have to reinvent the wheel to do so many things. The WordPress core comes with a huge codex of functions that do most things you’ll need - posts, comments, pages, adding users.
Even when the WordPress core doesn’t solve your problem, chances are, somebody else has, and wrote a plugin for it. So you can leverage the work of others for further custom features.
Furthermore, WordPress is built in a way that it is simple to customise and easy to extend through things called filters and hooks. These let you add new functionality or change behaviour in a modular way, without hacking into the WordPress core. The modularity of plugins enables you to pass on what you’ve made to others who may even improve upon what you’ve made.
All in all, there’s a massive community of learners and teachers out there, all sharing tutorials of how to make different features - whenever you’re stuck, there’s someone out there willing to help on sites such as the WordPress Stack Exchange.
2. CMS Knowledge
All frameworks are not completely different, and a lot of what you learn developing WordPress sites is transferrable to other frameworks.
It’s essentially a CMS system - and will teach you a lot of the main concepts involved with a web application. For example, when adding your own functionality to WordPress, the beds way to do so is through making a plugin.
You can structure your code however you want in this plugin - you can develop with your own classes, and make use of MVC frameworks..and it can be as large as you want. For example, there are e-commerce plugins such as WooCommerce, which contain huge amounts of code - structured in whatever way the developers of that plugin chose. They’ve effectively built a whole e-commerce system which simply runs on top of WordPress, as a plugin.
3. The Job Market
As previously mentioned, WordPress powers around 20% of the web, so it’s popularity makes it a solid framework to learn as there’s a lot of WP work out there. As a taster, here are some of the most well known sites using WordPress - and you never even noticed:
I found these sites from the article: “40+ Most Notable Big Name Brands that are Using WordPress40+ Most Notable Big Name Brands that are Using WordPress”, where more examples can be seen.