Blizzard explain why adding more space to the stash isn't a trivial matter and how the stash and player interaction systems are connected.
Turns out they can't easily add more stash tabs as the game pulls the entire stash for every person you encounter. This leads to memory and performance issues. They need to fix this before they can add more stash tabs.
I think it's really defining that they are not ashamed to commit such bs and even tell us about only to settle it at "more than 1 is not possible", such bs
This is the 4th game and Blizzard doing this since 30 years, what a bs excuse
And they have enough examples of other arpgs to know stash tabs matter. PoE for example you need tons of tabs and can buy more (not at all saying D4 should do that).