That sounds like total overkill. To deanonymize a reddit account, it is easier to just use a add/cookie/script on reddit to link it to your facebook account you have open in another tab.
Ok, I don't know about any reddit details, but I just opened reddit.com without a adblocker and took a look in the network tab in the dev tools.
I mean, I don't see a plain facebook connection, but I see googleads and amazon connection and don't know what else obscure things. I doubt it would be hard to sneak something in, that just checks whether this is the same browser where you just switched over from the facebook tab (where the onblur event just got captured). But again, I am not an expert in tracking ads, nor reddit, I just know the web and its various data transmitting technices quite good.
