In reply to Ciprian Popescu.

Of course but "Deferred On The Fly" generation is very different than TimThumb/phpThumb.

For one, you could send any pixel dim you wanted to phpThumb/TimThumb and it'd attempt to generate it via a public API.

It was, for a while, an easy way to DOS a site by asking it to generate 1000x1000, 1000x1001, 1000x1002, etc... images endlessly. Even though each one got cached you could ask for infinite image sizes.

WP however would continue to have predefined thumbnail sizes and not open to requests for other sizes from the front end.

Deferred OTF - would reduce CPU usage AND file storage. It really does make a lot of sense from a performance benefit point of view.

Folks promoting this being "on by default" because that'd have the maximum benefit to existing sites, seem to ignore that face that most older large sites have image URLs hard coded in the content. They will not magically start serving the WebP version for old content just because WP has generated it.

Almost no one objecting to this is objecting to WebP generation in core, or multi-mime. It's solely an issue with the implementation that is on by default on existing sites and lacks a simple user facing option on the media page to enable/disable it because it has the potential to take down sites unexpectedly. The example the WordPress Photo Directory immediately starting to throw fatal errors and failing image uploads ought to give everyone pause. https://core.trac.wordpress.org/ticket/55443#comment:123

If it's a problem on that infrastructure... yikes.