The one issue I have with that is that all the counters are situational.
Well thats what building a good team is all about. If your put up agaisnt a UB and you often struggle with spit, its only your fault if no one took a general or took the Symbol of Purity (which anyone can get).
Of course you cant counter it every time with no thought or planning - that would just make it useless.
There will come a time in the game where you will need to hold your lane on your own, and if you've just been relying on Sedna's heal all game, you could very easily die..
Well if your Rook you should have lots of HP and possible armour - the counter to UB. And by putting up towers you should be able to easily hold your lane vs a UB if your playing well.
If your Unclean Beast, well its spit vs spit so you cant really complain.
And if your any of the generals, you have a nice counter to it (I admit QoT's is a bit less of a "counter") and so that should be no problem.
The only two characters you will have problems with spit is are Regulus and TB - whom are both ranged. And if you ask me, if a TB or Regulus could hold a lane vs UB then that would just be plain stupid.