I miss the point, Alexandre.

What are the arms, but the collective of stars and solar systems?

If I follow you, then all stars and solar systems are going faster than their collective. It makes little sense to me. Or are you saying that our solar system is special?

We do not see a full dissolve of arms in galaxies known to have arms, do we?

Can you explain is simple words how our solar system goes faster than the nearby stars and systems?