Stuff like datepickers, autocompletes and whatnot are very consolidated in jQuery world. Sure there are options for vanilla JS but they are not mantained or do not have all the features.
These components are being built for the Reacts and Vues frameworks these days.
Personally I like jQuery. Like so many developers I started using it a long time ago because it solved numerous browser inconsistencies and incompatibilities. Then I got used to the clean and concise syntax. Now I use htmx more than jQuery.