Scandinavian origins of Mieszko I

Since Vikings placed fundaments for state of Rus, some wondered if is that possible, that they were also founders of Polish state?

There are some arguments for that theory:

1. In first written document, Mieszko is called "Dagome" which could be Norman name - as Dagon.
2. There are some Viking weapons found in Poland
3. There was a Viking city nearby, called Jomsborg?
4. Some of polish noblemen had Runes in their coats of arms.

These are however, most historians think, very weak arguments.

1. In no other chronicle or document Mieszko is called Dagome. Quite contrary, he is described as Msko, Mesco, and so on - both by Ibrahim ibn Jakub, who was describing Poland in that time, and by Germans. Dagome Iudex, what's more important, is a terribly mangled copy, or rather a summary of document. For example, to this day historians are arguing what does ,"Shinesghe" mentioned in that document means. Copyists who made that summary even didn't know about whom he is writing. He could have easily made more mistakes.
2. This is proof that Vikings were merely mercenaries or invaders. What's more, the findings relating to them are few, especially compared to Russia and other countries.
3. In fact, some (like Awdañcy) had signs which can be interpreted as runes, becaues there is slight resemblance between runes and that signs. However as well they could be something else, for example special ownership-endorsing markings. And even if some Polish Noblemen were of Viking origins, this could also be attributed to the Viking mercenaries of Polish kings.
4. Jomsborg?, as historians (at least Polish) have agreed many years ago, is a myth. The only source that tells us about Jomsburg are Sagas from Island, from the 13th century. More probably there was city of Slavic pirates at that place.
5. Dynastic tradition is straightforward in saying that Piasts originated from local population. It does not mention Vikings, contrary to dynastic tradition in Rus
6. There is no archaeological evidence of rapid changes in the making of weapons or fortresses. Quite contrary, the evolution in their making is gradual. Fortresses are made in a way that not resemble the Viking customs.
7. There is strong evidence, both archeological and written, that the Polish state developed on its own.