It doesnt work for everyone, I always use firefox auto-mulitcontainers where each tab has its own container with no history and cookies and I still get blocked by medium
Often when using incognito doesn't work for "limited free articles" paywalls it is because you haven't restarted your browser in a while and have had incognito windows open for a time too. Session cookies happily persist in incognito windows while you have them open and are shared between such windows.