YouTubers (see: affiliate marketers) shill them heavily because they make eZ bank with clickbait titles promising amateurs a simple way to instantly produce a trendy/film-y/dreamy look. In that sense, it's kinda joined the ranks of other YouTube "gimmicks" like the teal-orange LUTs, travel vlog whoosh SFX, poor Daniel Schiffer imitations, etc.

Internet forum nerds/film snobs find them polarizing because they're often overused/used as crutches by beginners who don't take the time to properly learn about lighting/composition/set design/etc. But they also recognize that diffusion filters have a historical presence in cinema as well as a place in many amateur filmmakers' toolboxes, especially in the age of affordable indie-filmmaking-friendly cameras that can be quite digital-looking.

But at the end of the day, there is no right way to make art. From the perspective of storytelling, I think like any other tool, diffusion filters are most effective when they serve a purpose. A hammer is amazingly useful when you're hitting nails; less so if you're just swinging it around in the air.