I think the skepticism comes from the recent OpenAI/Oracle deal which seemed kind of circular due to paying with equity whose value was being inflated by the deal itself (if I understand it correctly). This deal seems more like an outright gift of equity if OpenAI goes through with the deal - so it could be thought of as almost a rebate or net discount on the cost of the GPUs.
As @stingraycharles notes above, the AMD stock went up a lot already and this "may finally enable AMD to get a foot in the door in the whole large scale AI market."
Again, I'm in no way denying either that (1) exists or that there's almost certainly an AI bubble -- I just think this difference is material.
For example, I would classify the recently proposed deal between NVIDIA and OpenAI as a case of (1), but this deal between AMD and OpenAI as (2). Namely, because I think it's clear that the chips act as well as recent advancements by Chinese manufacturers are threatening to NVIDIA's market-leading position and OpenAI investigating new vendors suggests they have suddenly become concerned with reducing cost of goods. Indeed, if both the leading Chinese firms and OpenAI were shown to be able to work with other vendors without sacrificing speed to market it would materially impact NVIDIA's stock price. AMD, on the other hand, is not trying to subsidize an existing client, but convince a market leader to take a risk.
The NVIDIA deal, then, suggests to me that certain limits have been reached in the industry, while the AMD deal does not provide me with any further evidence as to the existence of a bubble.
You can see this play out in the history of OpenAI. NVIDIA supported them from an early stage and in exchange received OpenAI equity to offset the risk. Now from a position of relative strength, OpenAI has become concerned about vendor lock-in and so is rationally exploring AMD. Yet, because any such deal will materially impact AMD’s stock price and there is risk both of losing time trying to train with new chips as well as of benefiting competitors if they work with AMD to improve their hardware offerings/APIs, it is reasonable to ask for equity upside. So, for the same reasons (increase in stock price and enterprise client who will help improve their product offering) only without risk, is it understandable why AMD would want to offer equity on such favorable terms.
TLDR; My sense is that the sudden skepticism towards this relatively common enterprise deal structure seems to derive from the understandable interest in identifying signs of an AI bubble. Such a bubble may (and indeed almost certainly does) exist, but I don’t think this is evidence thereof.
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EDIT: I'm just clarifying something I saw in a lot of responses. My only point is that it is important to try and empirically tease out what represents: (1) a circular deal in which vendors facing the limits of growth are subsidizing vulnerable clients; versus (2) a risk-hedging deal in which a non-market leading vendor offers upside to a market leading client.
I believe the recent Oracle and NVIDIA deals are cases of (1) that provide evidence of an AI bubble, but that this AMD deal is most likely a case of (2) that provides no further evidence.