I fail to see how this would limit roleplay since it is about ancient times, and in reality could be roleplayed as a part of your character or just as easily ignored. By legitimizing it I can only see how it would allow more events (of discovery, ancient magic spirits or old seed artifacts or whatever im not an ET). If it would actually tie anybody's hands in a practical way, let me know how.
Anyway, if the only lore that is accepted is Seeds existed at some point, then there is no drawback for that.
It doesn't have to specify that every wood elf did this (although it would lend some credence to wood elves being a subculture despite having no backstory). Just an opportunity for people to invent more creative backstories for their characters and participate in more roleplay with their fellow woodsies. Yes the culture itself is practiced, but having it be based, in some small way, in truth (as many are) would open up possibilities to make the culture more intriguing.