Learning the difference between server-side and client-sided data, and how it affects things like stash or inventory space..
some games are built to be server sided, some are client sided, and some have a mix of both, let me help you understand a bit better.
client sided data is easily described as data that sits on the user end, in your storage.
server sided data is easily described as data that sits on the developers servers.
when it comes to inventory in some games, the developer can choose if they want the items to be stored client sided or server sided. Division 2 seemed to be developed in a way where there is A LOT of data that is stored server sided, there's pros and cons to this.
pro's is it eliminates tampering or modification of data, if items and gear were dropped to us from the server side and then turned client sided when we picked it up, i guarantee you there would be rampant cheating with modified weapons that easily would break the game (see borderlands as an example) and quickly ruin the online aspects of the game, keeping this stuff server sided ensures that this doesn't happen, or makes it much much more unlikely to happen.
the con's of this, servers aren't cheap, and storage isn't cheap, having so much data on a server side costs a stupid amount of money to upkeep, this is why we see limited stash and inventory space per account/character, all the trash gear we store gets saved and stored on their servers, now imagine how many players play this game, how many have multiple characters and how many times we call to these servers when we play this game, it all adds up.
if this game's stash and inventory were handled client sided, we probably wouldn't have space issues since stash/gear would be stored on our end, but as mentioned above..it opens a gate for players to cheat and modify game data much easier, in a game with PvE, PvP, PvEvP.. you can see how this would become a huge plague on the game.
many people have said they'd pay for more storage, i actually kinda back this idea because if they need to upgrade their servers to maintain proper server performance vs player data storage, then paying for extra stash space should help that cause.
..or, do something like what Monster Hunter World does, because a lot of player data including inventory was handled client side, it led to many people cheating to get items and stuff they shouldn't by modifying save files, but recently they changed it so the game does a check upon loading in and if there is data that doesn't match this check, you're denied entry to the "online" aspects of the game.