It's false.
Tennessee 1998 has a listed attendance of 49,550, which was capacity at the time. The game against Miami that same year is listed as 49,521 -- I'm gonna call 28 seats under capacity a sellout. Michigan in 1999 is listed as 49,249, which was the new listed capacity for that season (I recall we removed some seats for wheelchair access). So... sellout. I mean that's 3 games alone.
There are a number of games in the 90s where attendance is listed within 100 or so seats of capacity. Those are sellouts.