The characters here are unbelievably stupid

The way I see it is that the characters in Ghost Dimension were the unbelievably stupid ones, the cast from the previous films still had reasons for their motives, not aware of what's really going on until it gets to that point of 'no return' Katie and Micah especially because they had no idea what Toby really was and why he wanted Katie so much, Katie had her memory wiped and so only remembered being haunted in her childhood years by something evil, and the house fire, the only knowledge they receive that doesn't even help them is from the Psychic and the dead girl Diane's website, Micah worsens the issue though from constantly taunting Toby and basically everything that happens is the result of him, but even before that they had good reason to not get help from an Exorcist because of what happened to Diane, Katie's family however had more knowledge of this phenomenon and were THAT close to almost getting rid of Toby, they just weren't aware that transferring it to Katie would kill Micah and sister, brother in law, then abduct her nephew.

And it was already established in the first film that Toby would just follow them, a classic symptom of Demonic Activity, they will literally latch onto you and not let go, they don't haunt houses like spirits, they haunt people, but of course all they had to do was wipe the symbols on their daughter's wall, done, no Portal, no Prophecy, but they didn't and honestly deserved to die for their sheer stupidity, and the infinite paradoxes and plot-holes just ruined this film even more, it held no candle to the first films, even The Marked Ones which was 10x the sequel let alone 'Finale' this garbage was.

Agree with everything you say. They are unbelievably stupid. I would find it easier to believe ghosts are real than that people are this stupid.

Especially after they capture Toby on tape. I'd be getting the hell outta dodge once I saw that, and moving to somewhere with way more people around. Surely Toby wouldn't be able to use his power against lots of people.

I'll add one:
You can't find your daughter in the house at night, run around wildly with flashlights, instead of turning on the lights for normal visibility.

To be slightly fair, they only returned because supernatural forces transported the little girl back to the house, but even then, why stay in its favorite haunts instead of enacting the ritual somewhere removed from the "entry point?

It also might have been easy enough to dismiss the part in the vid where the little girl described the brothers viewing several herself on a tv as a coincidence, but combined with the other events, anyone concerned enough to have been placing cameras around the house would've exited the premises far earlier.

Other clear failings:

How did the mother completely dismiss the fact that the fireplace gas valve actually squeaked open feet away as she leaned inside, or that something practically knocked her over seconds later? Next scene she was more concerned about the fate of the bible and rosary that the inexplicable opening of a valve which could blow up the house.

Also, given that inexplicable event, how did they possibly not view the footage on the magic camera to see the swirling mass of doom descending from the entry point above the living room, or the figure it coalesced into?

And how did they not see the part where the portal in the wall opened the first time? Esp after the kid briefly disappeared?? What's the point of having a magic camera if you aren't going to check it when the really weird stuff is happening? To be fair again, this started becoming a regular problem in all the sequels, but in this case, they only had the one camera capable of actually seeing the paranormal.

It all reminds me of this Eddy Murphy routine:

https://www.youtube.com/watch?v=InLfUMjyKNo

"I like to watch."  Chauncey Gardiner, 'Being There'

I'm also wondering why they didn't just clean/erase the wall above the daughter's bed. Yea, she could've just redrawn it, but it might have taken longer for the dimension to from. Or maybe put Leila in another room?

90 minutes of unbelievable character reactions created by unbelievably lazy writing. Add on-the-nose dialogue, paint-by-numbers directing, wooden acting and home-computer CGI, and the result is a plodding snorefest.

The most entertaining part of this film is watching it with the captions on. Seeing line after line of lame dialogue written out is hilarious!

I totally agree with your points. Those characters are so stupid.