It can (that's why it's being pursued) and that, ironically enough, could even empower decentralized and P2P networks. Hear me out.

If you look at the history of the internet it's basically a story of decentralized protocols with a choice of clients being outcompeted by centralized services with a single client, usually because centralized services can control spam better (+have incentives to innovate etc, it's not just one issue).

Examples: USENET -> phpBB -> reddit, IRC -> Slack, ISP hosted email -> Gmail -> Facebook Messenger, SMS -> WhatsApp/iMessage, self-hosted git -> GitHub.

The reason spam kills decentralized systems is that all the techniques for fighting it are totally ad-hoc security-through-obscurity tricks combined with large dollops of expensive Big Data and ML processing, all handled by full time teams. It's stuff that's totally out of reach for indy server hosters. Even for the big guys it frequently fails!

Decentralized networks suffer other problems beyond spam due to their reliance on peers being trusted. They're fully open to attack at all times, making it risky and high effort to run nodes. They're open to obscure app-specific DoS attacks. They are riddled with Sybil attacks. They leak private data like sieves. Many features can't be implemented at all. Given all these problems, most users just give up and either outsource hosting or switch to entirely centralized services.

I used to work on the Gmail spam team, and also Bitcoin, so I have direct experience of the problems in both contexts.

Remote attestation (RA) isn't by itself enough to fix these problems, but it's a tool that can solve some of them. Consider that if USENET operators had the ability to reliably identify clients, then USENET would probably have lasted a fair bit longer. Servers wouldn't have needed to make block/allow decisions themselves, they could have simply propagated app identity through the messages. Then you could have killfiled programs as well as people. If SpamBot2000 shows up and starts flooding groups, one command is all it takes to wipe out the spam. Where it gets trickier is if someone releases an NNTP client that has legit users but which can be turned into a spambot, like via scripting features. At that point users would have to make the call themselves, or the client devs would need to find a way to limit how much damage a scripted client can do. So the decision on what is or is not "approved" would be in the hands of the users themselves, in that design.

The above may sound weird, but it's a technique that allows P2P networks with client choice to be competitive against centralised alternatives. And it's worth remembering that for all the talk of the open web and maybe the EU can do this or that, Facebook just did the most successful social network launch in history as a mobile/tablet only app that blocks the EU. A really good reason to not offer a web version is because mobile only services are much easier to defend against spam, again, because mobiles can do RA and browsers cannot. So the web is already losing in this space due to lack of these tools. Denying the web this sort of tech may seem like a short term win but just means that stuff won't be served to browsers at all, and nor will P2P apps that want to be accessible from desktops be able to use it either.

Anyway it's all very theoretical, because at this time Windows doesn't have a workable app-level RA implementation, so it's mobile-only for now anyway (Linux can do it between servers in theory, but not really on the desktop).