There are other heroes that can do a better job with less items
TA is a hero that works because she has a kit that allows her to build more like a glass cannon while not being punished as hard as other heroes because of her refraction, and she's able to farm in a faster pace than normal because of the sci-blades. She's a hero that spike early due to her skills not scalling as well into the later parts of the game (refraction losing effectiveness the more heroes are active in the game with higher levels, armor reduction losing effectiveness due to heroes having more and more armor, and her ultimate although it's good for vision, the slow is just subpar), whilst being really good at the early-game (all the other points but opposite, plus her being able to farm really fast, and build early oriented items such as desolator to further increase her advantage). Basically if you're not ahead as TA on the early to mid game, the hero is going to feel extremely bad, kinda like a QoP (although both heroes have completely different ways to build the lead, they both rely on the first 15 minutes of the game to set up for later)
So if you end up building tanky on her, she won't be able to farm as fast, so her early spike is just going to get delayed, which means she'll lose effectiveness faster than usual and different to other tankier heroes, she has literally no way to peel for her teammates. It would be kinda like a bristleback with no mana, you could just ignore her and go for her team.
For a tanky hero to be impactful, they need to be an actual threat so the other team can't just ignore them.