Speaking as a former FLL student, I don't think it would be right to consider FLL teams "new" every year. Granted, my team was home-grown rather than started by an FRC team, but we kept the same coaches, build space, name and theme each year, and became very recognizable at competitions year to year. Membership turnover wasn't that high either, with many members sticking with our team for 4, 5, or even 6 years. We just didn't identify closely with our team number, since it changed year to year. *
I realize many (most?) FLL teams are not like this, but making the generalization that all teams are "new" each year seems a bit hurtful to the more sustained FLL programs.
*Looking back now, I find our team numbers kind of funny. Through various years, we got to play as FLL# 1114, AND FLL# 111
