Quite strange that the core developers would decide to make an URL translatable, it is actually a case here of over-doing something. But anyways, lets get to the main question
PHP vs HTML
Although there are many reasons I can think of why one would prefer PHP above HTML, and that goes for the core developers as well, the main reason lies in one big difference between these two different languages
- PHP is dynamic language and HTML is static language
This means that code written in PHP will update itself according to the condition/s set for that specific operation, it does not need human intervention, while anything written in HTML will remain the same until someone manually updates the code to reflect changes, so it requires human intervention. Not having to manually update a single line of code or a thousand lines of code when changes are required is one of the main reasons PHP is used and prefered above a language like HTML
I do think your main issue is that you are still very new to PHP and do not really understand the language as such, which is actually a great opportunity then to dig in PHP and to learn the basics to get you going
As to your exact question, there is nothing wrong swopping PHP with HTML, but you will loose the dynamic aspect of PHP