Before we get into a live action debate, the submissions Commander Lizzardis referred to (e.g. #819193, #819043) were lazy edits of night club videos made with Wondershare Filmora and ripped from YouTube videos, not informative documentaries or stuff like that.
I'm also all for more content in the portal but the guidelines are quite clear about submissions that aren't the user's own submission, and we don't want to bother the NG moderation team with tons of links to the "original DailyMotion recording of the original YouTube recording of the original music video/live action" nor spend an eternity trying to find all of the tidbits stolen from other content for each submission.
Nothing against any engine that isn't explicitly forbidden by the Portal Guidelines. Recording oneself doing stuff that should be directly submitted is not animation, this has nothing to do with the engine used. A game submission example would be recording oneself playing a Scratch project - Scratch isn't the problem.
For content that NG moderation had considered and debated, the guidelines are as follows:
Do not submit Let's Play videos or anything that primarily depends on recorded video game footage.
We usually report this under "gameplay footage" unless it's an obvious parody and not just the user recording themselves doing stuff.
Do not submit something that is merely a sound visualizer set to music, or a recording of your music project timeline. If you want to promote your song in the movie portal, it should be set to original animation like a proper music video; otherwise stick to the Audio Portal.
Usually ends up here as "no animation" or "should belong in the audio portal".
Do not submit speedpaint / art timelapse videos. We would like to accommodate these in the future but for now your best option would be to embed a YouTube video under your finished art entry in the Art Portal.
Confirmed with Commander Exedor in DM that these could be flagged as such but took some time to clear.
Now, as for live action as in actual live action (an example would be live documentaries for the informative section):
Our focus is on animation. If you want to try live action here, it must be a short film with legit production value and preferably some animation component done in post production.
The NG moderation team has probably asked Tom about this countless times over the years.
Hopefully this clears things up! Thanks and please let me know if I'm crossing boundaries with this post.
Edit: Stealth typofix.