I use the network to host the webxr experiences, which are bundled wasm files, from unity. All of the code lives on the blockchain so, in this sense, i really couldn't do without it.
If you are referring to blockchain-specific functionality, then this is largely true, however i have implemented some demostrations of the consensus mechanism being used from inside an immersive space. This is really to illustrate that it is possible, rather than try to sell you a meme coin.
In the near future I expect to be using the ICP for a lot more, however, since it provides some rather interesting technical opportunities. It is wrapped around something called a 'network nervous system' which acts as a sort of administrator for proposals, so your point about abstraction is accurate, but this is the case with any large vendor.
I choose to build on the ICP because it is more secure and straightforward for my particular stack, plus it has a lot of potential, despite the noise. I've implemented webrtc messaging to keep the cost of normal multiplayer data transfer as low as possible, because consensus is expensive and the network runs on a pay-per-use compute model.
I'm offering a new route, outside of big tech, if you don't consider Unity a menace, which i acknowledge that some do. I am taking an admittedly more radical stance, by including the hosting in this.