Do combat arms soldiers look down on fellow combat arms brethren if they have deployed and not been awarded a combat badge/medal/ribbon?

This sounds like the crap that goes on in high school: everybody gets a trophy. Not every MOS is eligible for badges. I have a CIB and I earned it. If you don't, so what; you're helping the overall effort and that's all that counts.

Or their S1’s and CoC’s could have simply dicked them. I know several guys who still have CAB/CIB packets still pending from 2012-ish.

Last I knew for Medics you can only get the CMB. You also must be supporting the right kind of unit and treating patients while under attack. There for awhile they were saying that only the primary medic (the highest ranking or the one that was charge) could receive the badge. Most medics under fire may also be treating patients and will still never receive this. On the other hand I have heard of some units that the minute a rocket comes in all medics receive it. I think that until solders see this going on that they do look up to the badge until they start to see how two medic with the same circumstances where one will receive it and the other will not. They can be in the same place and doing the same job but be assigned different unit or other such problem.

I was in the mech unit but was still awarded one.

No I do not, It is not the fault of the soldier, it is the fault of the person in command who refuses to acknowledge the courage and facts that these men and women have been in combat. If you have been in combat then you need to be awarded a combat ribbon at the very least.

They use it as a pecking order tool. I have a CIB and because earning my EIB (one of only 3 in our Regiment 505 PIR) was such an honor when I got it I wore my EIB on my BDUs. I did wear my 82nd combat patch. I wore my CIB with Star and Combat Jump Wings on my dress uniforms but not on my BDUs. Originally I felt Grenada was a poor comparison to my dad's CIB. After Bosnia and Afghanistan (in the 80s) I felt like I had more than earned it yet it was a thing I did at that point and everyone that mattered to me knew I had lots of time in the mix and never cared what I choose to wear. When I was still in the 82nd having a CIB was like a free pass to be lazy for some and for others it was like a rank multiplier Spec 4s with would lord over sargents without. We would only put CIB holders in squads with NCOs that had CIBs.

You can look at it any which way you want, but unless you are Infantry, you will be looked at differently than those hat are. I’m not Infantry and when I deployed I was Combat Support. Combat support elements have the potential to see just as much action and the nature of warfare being what it is makes every deployed individual a potential combatant. I just say don’t worry about it. Who cares what other people think about YOUR JOB! Everyone has a function and we all know the individuals that under perform. I will say that you also do t have to wear your badges. That is 100% an option.

And worse if you are a REMF.
As a medic I was only "regarded" when I was an infantry medic

Yes, sad but true. A common theme was, “I see you are wearing a combat patch, but no bronze star?” Guess you must have done something wrong huh? Unfortunately, I’ve been in some units that roll out Bronze Stars like a prize from a bubble gum machine.

Seeking enlightenment.
Its my understanding that the Infantry is the Queen of battle, and receives a CIB under certain conditions.
I also understand that Engineers are NOT granted the same award for keeping the bitch from getting raped.
Any truth to that.