Congrats on the successful tournament!
Plunging EBs is a common rule among leagues that play on location. For example, FSPA rules allow the player to play one earned EB, any additional EBs must be plunged.
I think that plunging EBs for a location tournament makes plenty of sense. It is not always possible or desirable to change all of the games over to no EBs for a location tournament.
Typically tourneys do not allow EBs, so a simple way to not play the EBs is to plunge them.
It can add to the strategy of the game as well. If you have bonus held (or are playing a game like ToM, RS, HG, etc. where even bonus on a plunged ball can be significant) it might be worth going for EBs, even if they must be plunged.