There are some things that need lots of TempDB space. Let's take that 850MB table of yours, say a query needs 10% of it and needs to sort the results. That requires ~35GB of sort space. That's either in memory or it's in TempDB, I somehow doubt you have 35GB of memory available for a single query to use (that's above and beyond the buffer pool, plan cache and all other caches), so the sort spills to TempDB

CheckDB uses lots of TempDB. Index rebuilds use lots if you're doing sort in TempDB. Snapshot and read committed snapshot isolation levels use TempDB. Triggers use TempDB. Temp tables, table variables, hash joins, spools, sorts all use TempDB.

Before you conclude it's flawed logic and idiot devs, take a look at what queries are using the most TempDB space and investigate why they're using so much.

Personally, I think you're a little low on TempDB. I remember a 1 TB database with 120GB of TempDB space in total, and it used that space.