“When converting medium-resolution photographs (approx 1600px – 2500px on the long edge), WebP files are often larger than the JPEG equivalent,” WordPress developer Mark Howells-Mead commented on the main ticket for WebP work.
And from the comments:
This plugin will disable WebP generation by default. No settings, just a filter for those who can’t do it on their own.
Just from the point of not having many duplicates, jpg and webp versions taking up server space the plugin seems woth a though.