One of WordPress‘ great strengths is that it has been in continual development for around fourteen years. Thousands of developers contribute to the development and every update is tested and proven to work for all WordPress users all over the world – be it in a high-performance agency for advanced clients in Switzerland, or where it’s in use on old servers in countries where modern technology is either unavailable or unaffordable.
All of this work on the WordPress core is free and issued under an open source license. The Core can easily be extended by developers through the addition of plugins, be they complex or simple.
WordPress has always been developed on the principle of supporting the widest range of possible users. But, as in most web technology, there is no rule which says that you aren’t allowed to use more advanced technology when developing for WordPress. My colleagues contribute to the community-based open source aspect of WordPress, and the code that the developers write for public use is intended for use across the full range of environments in which WordPress can run.
For work clients, though, I use much more advanced techniques, which harness the full power of newer technology – for example HTTP/2 and PHP 7 – to deliver high-speed, efficient websites, which can be easily extended and developed according to modular principles. The WordPress Core team encourages developers to use technology which matches the requirements of their own projects, from advanced PHP principles to front-end technology like React.
Although it’s true that the WordPress Core still relies on technology which has been continually developed and improved over the past fourteen years, steps are being taken by Core developers and contributors to swap out pieces of Core technology for much more efficient versions in incremental steps. The shared-hosting solution at wordpress.com already uses a completely new administration tool called Calypso, which is incredibly advanced and which uses the WordPress REST API to communicate with the databases. The REST API became part of Core in 2016, and some parts of the administration environment for the self-hosted version of WordPress have already been improved through its implementation.