What does a tonearm contribute to the sound of a turntable?

Fluid damping causes all kinds of problems of it's own. The solution is worse than the cure. 
I went from various iterations of the original SME 3009 arm to various VPI arms including two of their 3D arms to my current two arms, Reed 3P's. 
I have had 9", 10.5, and 12. Steel, alloy, carbon, plastic (VPI 3D, call it "composite" if you like, it's junk IMHO), and now one Reed is 12" cocobolo and one is 10.5 in ebony. 
Just my opinion and experience-everything about the arm makes a difference. How it is tightened, how the vertical and horizontal motion is designed, the materials, the length and materials used for the armwand, shell, clips, wiring, hell, even the mounting and armboard materials have an effect on overall sound. 
Many of these things are not worth sweating about and some are. But they all have an effect on the overall sound. 
I use the same old analogy often but it is a good one. A pro can take a better photo with his phone than you can with a 10K Nikon set up. But that doesn't mean that the 10K Nikon set up is not worth the money in the right hands. Likewise, you can get great sound from a modest set-up if you set it up optimally. But.....

@hdm Thanks for the feedback. I have indeed damped the tonearm according to its specs, starting with two drops in the well so it's just under halfway.

@simao look at the Jelco 850. Big upgrade.

Larry needs to gain some experience  and knowledge before comparing a high end vinyl rig and quality acetate to the sound of a telephone.  That’s like comparing Lawrence Olivier to Popeye, or Raquel Welch to Phyllis Diller.  

Vinyl just has that tubey magic, well that’s what the guy @ better records proclaims! Lol...I love my vinyl and my many lp’s and phonographs...and you will have to tear them all from my dead cold hands! Streaming is for the lazy...jmo...its fun for discovering etc. But when I’m serious, its vinyl. Right now, I’m liking my pro-ject 9 inch carbon fiber/aluminum sandwiched tonearm with tpe damped counterweight on my classic sb table with a Hana EL moving coil, it sounds great with very little noise...put on the right record and its heaven...even though it’s not comparable to some other's mega buck analog rigs, to me, for now, it sounds divine. Not to mention, the classic is a joy to look at and use.