Xavi is a weird comparison for someone to bring up TBFMy brother go and watch a compilation video. I don't think you watched Xavi play, he was a thread of the needle passer. Through-ball was his middle name.
Do you know why that team was that good? A very large part of it was a little playmaker named Xavi.
Dembele couldn't take freekicks or corners due to his poor passing and kicking technique so that comparison isn't in your arguments favour. Would Dembele have gotten 5 assists for them in place of Xavi? I'm honestly not sure.
Truth to be told Dembele would never have played for them in that era. They wanted passers and deadly passers at that. Demebele's skillset was all wrong for them.
the nearest I’d say to Dembele would be someone like Viera but even he was quite different