When I encounter websites like this, I tend to leave and not return. However, Apple could alleviate some of this by improving the testing story for WebKit, which is sad at best on Apple platforms and becoming nonexistent elsewhere.
Of course there used to be Safari for Windows, but that’s so far out of date, not to mention the developer features it lacks, that it’s entirely useless. There’s also PhantomJS, an open-source “headless” WebKit browser, but that’s been abandoned for several years now and unlikely to return.
Absent an accessible way to test their code on WebKit, developers in many cases won’t test their code for it. When they can’t run WebKit tests, users will inevitably begin reporting bugs due to Safari/WebKit’s quirks (like the weird real-life bug I mentioned earlier in this thread). Since developers can’t easily test a fix given that many don’t have access to Apple devices, they will either advise users to switch browsers or attempt to disable the browser altogether.