Why using themeing engines

Drupal 8 uses the Twig templating engine
Drupal 7 uses a different templating engine.

There are many templating engines and handful of examples include
C# – razer, java – Thymeleaf, nodeJS – Jazz

I understand the need for these in languages other than PHP – the only other way to get the output of back end code into the front end page is if the WHOLE front end page is dynamically generated, without a templating engine ether the whole page is dynamically generated or nothing is.

But PHP has a feature which most languages dont.

In PHP static front end HTML and server side PHP code can be inserted into the file which gets served to the client.
So you can do something like this
< div>< li><? print(‘content’)?>< /li>< /div>

Which raises the questions.

What is the point of having templating engines in PHP at all?
Why does Drupal use a templating engine for inserting dynamic content into themes, what would be wrong with using something like this

< html>
< div>
<? Render(Drupal_region_Name) ?>
< /div>
< /html>

Drupal version: 

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