i think the point is that one actually burns disk space, while the other is just a nuisance for people on plans with limited data

You can store up to 80% of free disk space with indexeddb

https://rxdb.info/articles/indexeddb-max-storage-limit.html

using a browser is an easy way to burn disk space and limited data

light browsing is not a thing unless you somehow ensure javascript is disabled and all downloads are blocked