Don't kid yourself. SE would trade subscriber counts with WoW in a heartbeat. The two aren't close. WoW is doing it's usual end of expansion cycle decline, and it'll bounce back as soon as the next one comes out, as it always does (and XIV does the same).
Parsers were in WoW in vanilla, when it did it's rise to become the biggest MMO ever. It's not getting new blood now because at this point everyone who wants to play it already has at some point. It's 13 years old, after all. It's still the biggest MMO by far.
People who think WoW is dying because of parsers are so misinformed that it's comical.