To start, racing, like many performance oriented sports, is a "whole lot of monkey see, monkey do". Professional auto racing often comes down to "tenths" and the N
2 in place of the "80%" stuff is very likely in the category of leaving no stone unturned. Goodyear mounts all the tires used by NASCAR and in keeping with the 'spirit' are presumed to mount all teams tires with equal precision. Personally, I can see not advantage with nitrogen over 'dry' air whether dry by refrigeration or desiccant save "convenience and cost".
I've worked "crew" for a couple racers that used nitrogen but, not for any reason aside convenience. We used the same bottles for the pneumatic tools.
I once helped restore an old aircraft and worked part time in the service station. We added air to any tire that needed it. The air was from a compressor/refrigerated dryer/filter...I never heard of any problems...course that was in the late 1950's. I can see where the portability of nitrogen in today's airports could be an advantage, though.
In vintage racing, I use compressed air as I see no advantage to spending money for something that does nothing for my lap times. My tire sponsor has the ability to use nitrogen if requested, but very few ever ask. I don't even run my air through a refrigerated dryer, just the simple double water trap on my compressor. I don't live in a humid area, though. Works for me.
Isaac, I love the Jag story...I have a friend and owner of a local cafe that just bought a new Jag last year and has succumbed to the same mentality as your marketing guy. I'll never understand and I will never be able to do more than just smile and nod my head.

You have also quantified what I have instinctively known for 60 years. Thanks.
Rod