Does WordPress still ask for FTP credentials for each file operation?

Not quite right. WordPress only requests FTP credentials if it cannot modify files. That’s the important bit from Rarst’s reply. This all comes down to who owns the files and does php (and WordPress) have access via either the group and/or user to modify these files?

The default is to use php’s filesystem extension which does not require FTP at all. In the case of using FTP, credentials would always need to be set either within the WordPress admin for each request or in wp-config.php.

Here’s a good overview of what’s going on: What security concerns should I have when setting FS_METHOD to “direct” in wp-config?

The codex for FS_METHOD lists the different options for WordPress interacting with the file system.

To answer your question, nothing has changed with regards to the way WordPress interacts with the filesystem with regards to FTP.

Hope that helps!