WordPress is a CMS software written using the PHP programming language.
And just like any programming language, new versions of PHP will get released every year.
With every new version release of PHP, these things happen:
Because of these things, if your theme and plugins are not compatible with the latest version of PHP, WordPress will throw fatal errors that look ugly to our front-end visitors and destroys the website’s reputation.
This happened to many of my clients who were using age-old themes without updating them to newer standards and it proved costly to them.
So, it is important for you to make sure your theme and plugins are compatible with the latest version of PHP.
It’s okay if we don’t take advantage of the new features in our theme. Only performance will take a hit.
But make sure your theme is not using any old PHP stuff.