Here are some usability and conversion studies: https://conversionxl.com/dont-use-automatic-image-sliders-or...

https://unbounce.com/conversion-rate-optimization/conversion...

https://www.nngroup.com/articles/designing-effective-carouse...

Unfortunately clients or designers have these because they look nice, add some drama to a page, or because a competitor has one. So it really comes down to the goal of page (conversions, branding, SEO dwell time, etc.)