Required object config for threads/posts

[av8or1]

All-

Still relatively new to vB and have a question regarding exactly what is required when initializing/configuring your DM thread or post object prior to (pre)saving it to your DB/forum. Specifically, when conducting a search regarding this subject, one will see (good) examples such as this for the thread stuff:

$forumid=324;
$threaddm = new vB_DataManager_Thread_FirstPost($vbulletin, ERRTYPE_STANDARD);
$foruminfo = fetch_foruminfo($forumid);
...
$threaddm->set_info('forum', $foruminfo);
$threaddm->setr('forumid', $forumid); 
...

And then examples for posting to an existing forum go something like:

$threadid = 421;
$userid = 52;
$postdm = new vB_DataManager_Post($vbulletin, ERRTYPE_STANDARD);
$threadinfo = fetch_threadinfo($threadid);
$foruminfo = fetch_foruminfo($forumid);
...
$postdm->set_info('forum', $foruminfo);
$postdm->set_info('thread', $threadinfo);
$postdm->set('threadid', $threadid);
$postdm->set('userid', $userid);
...

What I am curious about are the above snippets shown in red. Is it really necessary to get the thread/thread-and-forum information and then set it as part of your initialization/configuration?

I ask only out of curiosity. I tried both of these examples without retrieving any information (via the fetch_[thread|forum]info() calls) and by simply setting the correct thread/forum ID in the object's data the threads/posts in my test appeared to show up ok and function correctly.

Surely though there was/is a reason for this fetch-n-set stuff, so I thought I'd ask. I'd prefer to "do it right" WRT the initialization/configuration of these objects, but mostly it's because curiosity often gets the better of me.

Thanks!