I'm very unlikely to be as social as you, but in the half-dozen-odd conversations I've had with guys before/after shows, I've never witnessed the in-crowd phenomenon at all. People in real life tend to not be like "Psssshhh Exodus, I only listen to REAL TRUE THRASH like Infernal Majesty or Protector". Instead they're pretty laid back people that might gush over their favorite bands, recommend some stuff, talk about some upcoming show, etc. The kind of defective personality traits that pop up on internet forums regularly aren't that common, just like how 25%-ish of forum users are INTJs while like 1% of real-life people are.
None Shall Defy does have a strong following, of course, but your "in the last 10 years" makes it sound like you're the lead pollster behind Gallup's Metal Tastes(tm) division. If you're saying that in real life, you've met a single "shits-on-thrash kvlt crowd person" that suddenly began liking None Shall Defy in the last ten years, I'm calling bullshit. None Shall Defy already had five glowing reviews on the Metal-Archives, btw and as someone that used to post regularly on the Canuck BraveBoard, I can tell you it was popular there too already. That being said, there is an in-crowd bias towards it, and I put Infernal Majesty on the second tier of my in-crowd list back in 2012, but that was exclusively a U-M phenomenon.