I wouldn’t say Margaery is really a counterexample.  They turned her into a vamp whose basically only play is flirting with people, as opposed to the book version whose political persona is that of an idealized maiden.

I agree that there have been changes, but the show has never actually done anything to indicate that he was involved.  And I thought at various points that they would.

Because this is the same plot as the books, where Littlefinger was not involved.

Because he wasn’t behind it in the books (it was Joffrey), and while the show never explained Joffrey’s involvement, it never actually identified Littlefinger as being behind it either.  Really, that plot thread was abandoned.

In the books, Dany isn’t fireproof.  In the show she is; she does the same trick in Season 6, for instance.

He spun the incident to his advantage.  He didn’t instigate it.

Littlefinger wasn’t involved in the assassination attempt on Bran.  He did manipulate Ned using the murder of Jon Arryn.  But Littlefinger’s biggest motivator is petty grudges from childhood, and he was always out to doom Ned.  He could easily have guaranteed Ned’s victory over the Lannisters if he had wanted to.

None of those people were positioned as the main character.

Littlefinger wasn’t trying to help him.  He arranged the whole scenario specifically so that he could screw Ned over.

That was a joke, not a serious spoiler warning.

That’s very strongly implied in the books at a few points (both by the layout of the scene and a subsequent statement by Varys to Tyrion), but has yet to actually be confirmed there.  You can see Littlefinger cheerily standing around during Ned’s execution in the show in the same manner, but this was never made…

He was used to give Littlefinger control of the Vale army, which is the plot function the writers needed from him.

I thought it was always apparent that the writers considered Robin nothing more than a plot device who they spent as little time on as possible; hence why they completely rewrote Sansa’s story to take her away from the Vale and had barely any interactions between the two.

That’s such a terrible scene in terms of character writing, and typical of the poor writing for Littlefinger that would become characteristic of the show.

Episode 402, the Purple Wedding episode.  In the books there’s that exchange between Joffrey and Tyrion at the wedding breakfast that is meant to clue Tyrion into Joffrey’s involvement; it’s not included in the show, but it was in GRRM’s original outline for the episode, with authorial comments about what it is meant…

It’s not a well-written story, I agree, but it’s clearly what GRRM intended (confirmed yet again by the script drafts released for his take on Episode 402, where he included setup for Joffrey’s culpability that was cut from the show subsequently).

News of Bran’s injury could have reach King’s Landing by raven. If Ned (and the royal convoy) have time to get to King’s landing post injury (recall, Bran is stabbed while Ned is away), then obviously there would have been time for a single rider(assassin with knife) to get from King’s Landing to Winterfell.

No, all she says is that he lied to Catelyn about the provenance of the dagger.

They were at the Inn of the Crossroads, with Catelyn unmistakably traveling in secret given her lack of escort.  He absolutely would know she was in King’s Landing.  “Suspicion” is all that is necessary in those circumstances, since the Lannisters are presumed to be conspiring against the Starks.

It’s logistically impossible for Littlefinger to have found out about Bran’s injury and then sent an assassin all the way to Winterfell to steal one of Robert’s daggers and then use it to kill Bran.