Investigators who merit other Investigators research are giving Campaign Managers [...] an assurance
That's not what the merit system is for, and you have no options for enforcing this anyway.
If users want to confirm (or deny) what's been posted they can make a post.
why bother going through all the trouble meriting posts individually?
Because (IMO)
that's what the merit system is for - to merit good posts, not just to give bags of merits to users.
For example if I want to read best recent posts and go here...
https://bitcointalk.org/index.php?action=merit;stats=topreplies... large merit dumps skew this picture. That's not to say I haven't done that, and you're right that it is really the merit sender's discretion how they choose to do it, but I need to point out that "going through all the trouble" does have value.
my main account posts more than this one and I occasionally give a lump out with it.
Like I just gave 27 to the pharmacist.
But if you look at my philipma1957 account I would think I mostly do 1 or 2 merits to posts.