basic thoughts behind companions?

I am sorry if that has been adressed already, couldn't find anything about it.
I am really wondering what the general thoughts behind companions were.
first let me establish a few basic facts:
Companions are chosen based on the mob type and the modifiers.
an accurate, cold resistant antlion charger will behave quite differently from an quadrilla with 'all damage shocks' and physical damage aura.
So either the basic idea is that it doesn't matter which kind of companion we take, in which case the companion in itself becomes entirely useless, or the idea is for us to get the 'correct' companion.
But if that's the case, what is the idea behind us getting the companion?
With spectres we just go to the mob type we want and raise them, this does not work with companions due to the specific mods that we want / need.
So, is the idea for us to play along, pause the game at every rare, look what kind of mob it is, read the modifiers and then decide to kill or capture it until we just happen to come along the correct companion?
This does not seem very useful.
Ofc, we could compare it to 'best' equipment but in most leagues we can actually trade and buy the gear that eludes us or try to craft it ourselves. This is not possible with companions, I can't squish two apes in a recombinator...
So basically companions are highly specific but enforced to be SSF.
Now I am wondering, is there anything I am not seeing concerning companions (apart from resetting specific zones over and over again to force the game to spawn the correct mob after hours of trying)?
What is the original intent the game devs had concerning companions, how is this system supposed to work, what was the way the devs decided to be the correct one concerning companions?
I refuse to believe that noone thought about how acquiring a companion would actually work so there has to be some design to this.