You make all this sound easy for some reason.
Do you remember how much shit Law had to go through to just find the SAD factory. He had to make deal with Caeser to cure his men and then he still months trying to the SAD processing plant. He even gives Caeser his heart
He made sure to make these unreasonable deals with Caeser because he believed Caeser was vain enough to let him do whatever without telling doffy he was there. And it worked. He bribed caeser enough to pull that off. Problem is Monet was a spy for doffy and so doffy knew Law was up to something from the get go.
Remember Law is doing all this alone because he didn't want to get his crew involved in personal vendetta.
You see how much shit Law has to go through just to find SAD? He becomes caeser's on call doctor, gives caeser his heart, spends months scouring the entire Island while pretending to be "on vacation" and has to act so inconspicuous that not only does caeser not know, but entire gen the spy Monet who law doesn't know about also doesn't know what he's doing UNTIL it was all too late. Not to mention we don't even know how much shit law had to go through off screen to even learn that SAD existed, and that SAD was on the island and that Caeser was this selfish vain guy who can easily be bribed and that the Smile factory existed.
Now you are saying Law should've easily just broken into Dressrosa alone and done months of reconnaissance in Doffy's territory where everyone in Doffy's family knows him and he also should've taken a detour to investigate the Toys that exist on the island which to his knowledge have NOTHING to do Smile or killing Doflamingo.
This is all shit that Law should've done OFF SCREEN somehow even though we see how much shit he had to plan and get right just for punk hazard to work out.
Really?