Page builders are plugins that take the place of the default WordPress editor. They allow for a greater design control than the default editor. Page builders contain a variety of useful design elements like, quote sections, counters, accordions, flip cards, sharing, etc.. The also give you the ability to fine tune CSS elements either across the entire site or page by page.

WordPress itself and its plugins often require new feature updates and security updates. Those updates overwrite all the previous coding and that means any previous changes you may have made to WordPress and plugin coding are lost during the update.