makes you a stash purist by definition 
whatever reasons you have for not wanting to use tools or mods and only using vanilla methods is that very thing
so has the devs 
You’re also conflating casul (1x playthrough players) with casual endgame players
Again, devs are fully aware of loot goblins and hoarders; their stance for those are you should use mods - that’s literally the official stance. They want there to be some form of a choice/decision in item keeping, infinite storage would not serve that vision, infinite storage would only serve us loot goblins “you’re doing the same mistake of only seeing your own perspective here” that you’re saying my argument falls short of (which isn’t mine but the devs remember).
And yes, even for regular endgame players i can see their idea having a place, because unless you’re a goblin like me, you wont actually need to hoard everything, there is enough space for what you “need”, even if it’s not enough for what we “want”. And more casual endgame players will then only “struggle” with that space limitation on a surface level, as they quickly realize “oh i’ll never use that item anyway because i’m not interested in making 10 different builds to try out this specific item”
If anything you could say the real flaw in the limited space/item choice philosophy “as it pertains to a looter game” is that it can then potentially either highlight or detract from the item pool, as one could get the notion there are too many trash items; so why should they be in the game in the first place if from a design perspective i’m meant to discard them (tho many loot games has that issue too anyway imo)
remember to make manual backups (and also that the game changes save location on your PC so you need to move the saves if using Steam)