First of all learn to read within context. Obito would be dead if Itachi knew how kamui works, due to that sneak attack. Unfortunately he didnt know how it works & in an actual fight between the two it wouldn't be a sneak attack so that statement is completely invalid.
& Secondly, are we really going to take the opinions of others into account?
Okay then, [
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] Obito moves at lightspeed, GG Itachi.
Lol Itachi isnt making a clone before Obito warps behind him. If Itachi manage sit then obito simply retreats via intangibility & attacks from long range with massive kunai & shuriken, or obito can draw out susanoo with a large scale attack.
Susanoo get's pulled in with obito before it can fully manifest, but anyways once susanoo is drawn out [assuming Itachi even makes it to that] all obito has to do it warp from underground again, susanoo makes Itachi a sitting duck, especially when it has no legs.