I can see why you are doing this, but shouldn't it be more concerned with the misuse of it?
If you will excuse the example;
Threadopener:
how big is the earth?
geek1852682369847698...:
40,000 km around, 12,000km diameter, ect...
/thread
Here it is used to say this is all the information you need, there is no further need for this thread. (Thus, end thread)
A miss use would be as follows:
Threadopener:
How's the best video game character?
Halonerd:
Master cheif p00nz @$$, hez w1ck3d @w3s0m3!
/thread!
FFnerd:
Sephiroth!
/thread!
Here it is used as a lame attempt at humor.
Meh, your call really, just my opinion.