you don't have to though!
if you want to do more pure vanilla, understanding signals is really useful — this basically powers svelte's runs and react's hooks and whatever.
I love nanostores, a 286 byte (!) state manager that lets you build highly reactive pages w/o the weight: https://github.com/nanostores/nanostores
flexible tools like tinybase (https://github.com/tinyplex/tinybase) and unstorage (https://github.com/unjs/unstorage) are also super useful
tools like this lets you build highly reactive, engaging sites that load for under 50-100kb