yes very good point you have here, as the case is with devices, the internet, the blockchain and other services there is, all needs a service provider to grant them access.
The same applies for Arweave, you still gain access using your normal service providers but unlike the blockchain, you exhaust less data and time when synchronizing a node, and also get better speed and effeciency in data storage.
for more infomation please read the Lightpaper https://arweave.org/files/arweave-lightpaper.pdf