FactsOnly -
I am a long-time reader of this site, and finally decided to sign up today to respond to your line of questioning.
I graduated from Maryville in 1977 and have lived in Nashville for many years. I see the situation in Blount County as very similar to what is happening in Franklin, Brentwood, Hendersonville, and other suburban communities around Nashville. The area is growing, and both new families, and those who want to move out of Nashville/Davidson County for whatever reason, are pushing the population of the suburban counties through the roof.
I believe the same thing is happening in Blount County as transplants to the Knoxville area choose to live in Maryville or Alcoa. The city fathers of Maryville (and Alcoa) have no control over that situation - they are responsible for the education of every young person who presents him or herself at the schoolhouse door.
I may be wrong, but I assume that you live a bit farther from a large urban area than Maryville is from Knoxville (16 miles). In your case, a more stable and unchanging enrollment is probably to be expected in your school system.
If the TSSAA recounted the enrollments every year, no one would ever get their nose out of joint about having to play a school they felt was too big for their classification, but we all know the chaos that would result if they realigned more often than every four years, don't we?