As one of the author of this paper, we targetted cloudflare worker in the first place rather than others to mount spectre gadgets because not a lot of cloud vendors use the share resource in the way they did as far as I know (maybe another several, but not as well known as cloudflare), or at least putting so many users in a single process space. So chip designers didn't fully take their security model in mind. Not sure whether this will change in the future.
