> I dunno, it seems like way more cost effective to use the first party tools but I'm not sure why they really want that. Are the third party tools just really inefficient with API usage or something?

No, the first party tools, even if they used the same number of tokens, gives them valuable data for their training.

Essentially, the first party tools are subsidised because it saves them money on gathering even more training data. When you use a 3rd party tool, you are expected to pay the actual cost of each token.