The dunking on 538 is pretty ignorant. Here's a line from Nate's final pre-election post: "The probable result of a 2016-style polling error would be a Biden victory but one that took some time to resolve and which could imperil Democrats’ chances of taking over the Senate." https://twitter.com/AlxThomp/status/1323906135817097218

It's weird that journalists — who constantly complain that people criticize headlines but don't ready stories — would call out a top-line number while ignoring the context provided on the same site every single day

538 doesn't conduct polls (with the exception of some debate stuff). Their model forecasts the uncertainty surrounding the polls. And Biden had an 89% chance because there could be large polling errors and he could still win. And guess what: That's exactly what's happened!