The real problem is that these characters actual meet too soon and are too meshed together.

George was influenced by Jidaigeki stories and quite often you'd get characters or their relatives introduced early on in separate scenarios who eventually meet and resolve the story.

So in theory I have no problem with young Boba and young Han, early Artoo and Threepio etc woven in the background if they are separate vignettes.

Having all these characters actually knowing or actually being related to each other is the real problem because it shrinks the universe and stretches credulity to breaking point. Having them all exist at the same time but only come together towards the end keeps the scale of the universe but makes those characters narratively important as cogs turning the workings of the story.

I'm a big fan of The Water Margin and in the titles you would see all these interesting characters in a march against the enemy but it would take weeks and weeks before you got to meet them or understood their background story.

It made that saga really interesting because an apparently minor figure would eventually become crucial while a major character in an episode would be disposed of and not turn out to be vital in the grand sweep of things.