There is a jungle in URF!!!
"but 1v2 top!!!"
if you are going top you should be prepared for 1v2. If you cant handle it on a decent toplaner (for urf) then you are bad and deserve to lose horribly anyways
I'll let the others go into detail about why sending two top is stupid in any mode if you have the option to jungle and camp people in a mode where dragon can be taken at level 3 or really level 1 by some champs.
ALSO
if there is no jungler then there should be 2 mid in some cases.
and 