While <?php ...> and its equivalents for ejs, asp, or jsp are useful and a defining characteristic of PHP, it is implemented carelessly and prone to injection attacks. Using an SGML processing instruction for integrating scripting into markup languages is only a means of last resort when SGML has much better, type-safe expansion and processing features. "Modern" PHP leaves embedded PHP more or less behind in favour of Java-like frameworks, custom template engines, and other code-heavy approaches. However, the more PHP becomes like JS, the less there is a reason to use PHP over JS (which is at least standardized and has an extremely rich ecosystem) IMO.
