The tac support arty will NOT fire if there is no vision, that's why you need it. If you didn't need vision it would be beyond OP.
I know it needs vision man, but I mean it's only useful when drop the arty and u can follow up with tanks or AT guns etc to take out the disabled tanks, so you should be always there and have sight easily with ur tanks or whatever assaulting units u've got and u never wanna drop it the same way u drop Air Supremacy etc hence u never need recon for that, if u know what I mean
(otherwise it's just a waste of 250 ammo if u're not there to finish off the tanks)