In the case of GitHub, it was likely for data reasons + wanting to own where developers do work (VScode + Github).
In the case of HuggingFace, honestly not sure as I'm not familiar enough with their business. But I can assure you that Nvidia didn't buy them for 13 billion cause HuggingFace were desperate. When you're desperate, you sell for less not more.
From Nvidia's side? You get to keep the shell game of where your money and hardware are going spinning on the table for a little longer. If the party stops, Nvidia loses a zero right off their valuation instantly.
And, as a side benefit, you get to place your thumb on the scale of the open-weight hosting ecosystem. And maybe even fund a Chinese Anthropic or OpenAI at a discount.
OpenAI just popped out an inference ASIC. Google is on their 8th generation of TPU. Graviton is out from Amazon. The hosting companies want Nvidia out of their finances. Full stop. Nvidia has to do something, or it's going to get swept away.