Popular PHP CMS software also relies on .htaccess. Wordpress for example allegedly powers about a quarter of all websites, and auto-creates an .htaccess file when you enable pretty links, which basically everyone does. Drupal ships with multiple .htaccess files.
Sure it's possible to adapt this code into Nginx configuration, but there is really no reason to do that. It's far easier to set up Nginx in front of Apache and get most of the Nginx benefits that way.
There really are a lot of platforms.
Equally, there is a truckload of LAMP sites out there (Linux Apache MySQL Php) to give Apache the edge on pure quantity. It's been the standard for personal site hosting and forums for two decades. That's a long lasting effect. That's not where there is value and work for developers though.
Can you cite a source for this?
In my practice, the servers behind nginx are usually platform-specific application servers, such as Gunicorn or uWSGI for Python.