So my suggestion is make fire spread enabled so flint and steel is actually useful against trees. Also wouldn't fire won't work against someone claimed land because it's claimed?
If fire spreads, and I put a log against someone's claimed wooden house, and set the log on fire, would it spread to their house?
I've watched videos on the grief prevention plugin we're using, and supposedly all claimed blocks are impervious to fire. The reason I see fire being disabled for burning trees down is due to the lag it can cause, especially when you have an entire forest on fire. That said, I'm pretty sure there are plugins available that don't disable burning down trees, but rather limit how long the fire spread will burn for; thereby preventing entire forests burning and causing lag to the server. I'd definitely like to see some form of controlled tree burning implemented with the flint and steel.
Would 100% need some kind of spread protection as The Law mentioned. No matter how big the map is, with the number of players there are, if someone decides to start burning our forests, it'll suck. c: