Why use goblins at all?

I’ve put a lot of time into Warhammer 3 but I’ve barely touched the greenskins. Doing a gorbad campaign now and I’m confused why you’d ever use goblins at all? Goblins are weaker than orcs in every way, each goblin unit has worse stats than its orc counterpart. Goblin archers? Orc archers are better. Goblins with spears? Used to be the only spear and anti-large greenskin unit, but now we have orcs with spears with better stats. Goblin big boss? Why use that even you can have a black orc big boss. Goblin wolf riders? Why use that when you have orc boy boys. Etc etc etc.

So what am I missing here? I understand that in tabletop goblins are supposed to be cheap filler and chaff units. However in total war, they seem useless. Goblins with spears have an upkeep of 81. Orc boys have an upkeep of 106. Is 25 gold per unit worth using a far worse unit? In my opinion, no. Skaven slaves are the same thing, you may as well use clanrats (I play a lot of skaven). So to me goblins in total war terms are the same as skaven slaves - ignored.

Are goblins just for thematic armies?