potentially unpopular opinion: i'm actually glad this doesn't happen. scramble is a bad mechanic because it requires people to be honest, and nobody is ever honest when playing an online game
back when i was still playing live TF2, people would initiate scrambles all the time for completely arbitrary reasons, usually just because they got killed a couple times and wanted to be on the winning team. people don't scramble because they want a more fair game, they do it because they want to win. there's a reason it's always the losing team trying to scramble
im not trying to point fingers at anyone here, but there are simply too many unscrupulous people out there, and i don't want my game to get interrupted because some crybaby on the enemy team wants to be carried. if you ever get stuck in a situation like a 20-minute stalemate on dustbowl, that's just indicative of the map being shitty and poorly designed, not that scramble needs to exist
and anyway, the solution to an entire team stacking one class at a time is to impose class limits, but nobody likes those so i doubt they'd ever get added