@Polaris75 - I get what you are saying and I'm not discounting that people script and that IDOCers make tons of gold and sell. I don't think anyone is denying that. I actually find it interesting what you have provided and I'm glad you went to the trouble. Since you went to the trouble of writing a nice write up on your stance I figured I'd take some time to do the same.
That said...
Nobody here has given much support that Scripting/IDOCing has any real correlation with Commission Vendors being bad for the market; at least it hasn't been proven from what I've seen. While what you (and some others) are saying about scripting can be 100% true that still doesn't prove anything about commission vendors because ultimately they can still put things on regular vendors or auction safes or spam in gen chat. Maybe if you said "Scipters are bad for the market" I'd agree but using commission vendors as a scapegoat doesn't make sense.
This is getting a little off topic from commission vendors but this goes back to my original point. Supply and Demand (combined with opportunity cost)! I'll give one more attempt at explaining it while using an example.
Let's take soul seeker as the example. If the "going price" is 750k and there is a balance in supply/demand. Now someone scripts an IDOC and just so happens to get 20 soul seekers and they decide to sell all 20. There is now a surplus in supply so if demand isn't also increase (which if we are being honest it won't as the price original price of 750k reflects) the price will need to be lowered to generate artificial demand. For argument sake let's just say that forces others to also make price cuts and the scripters buy up ALL the soul seekers under 750k. Great... now they have to buy basically every soul seeker out there so they can fully deplete the supply and charge a new asking price to artificially inflate the market. Now it's STILL up to the public to set the demand because if the scripter charges 2M for something that had a going price of 750k that doesn't mean the new price becomes 2M unless the general population deems it possible and buys the higher priced item. That's supply/demand 101.
Layered into all of that is opportunity cost. I'm an average player that hunts things that drop a soul seeker. I work hard for them but put them on my vendor for 725k to try to undercut competition (does this make me as bad as the scripters for lowering the market price?). All of sudden the market artificially dips to 250k. It's up to
ME to determine if I want to drop the price that low or just keep it on my vendor at 725k (which BTW if it's a commission vendor I'M NOT CHARGED UNTIL IT SELLS!!.... but this is bad for the market right?). It's also up to
ME to decide if I want to stay in the soul seeker market... once I see how the market is on this item I'd probably stop farming soul seekers and look for another sought after thing with more demand and less supply.
I know this for 100% fact because not only do the laws of supply/demand support it but I've also seen this first hand. I used to make gold by taming high end GD or other pets and selling them off in Mag (or Luna)... I was in it for quite some time way back when things were rated 1-5 stars. There was always supply/demand at play and sometimes I'd take less on a pet I could get more for based on the supply of similar pets. I made a good UO living. Then the taming/pet changes came in and people just weren't paying the same prices they were before for a 4.5 GD or Cu Sidhe b/c pets could be trained up now. The supply pretty much shot through the roof of Cu's because just about any Cu would work and the demand actually shrunk (especially on GD) because people could get Cu's easily enough themselves (and were now on par with a GD). The time I had to spend to find a higher end pet versus what I'd get for said pet became extremely unequal (opportunity cost went through the roof). So... Supply & Opp Cost went way up while demand went way down.... Guess what? I got out of the business! I changed to do champ spawns are selling power scrolls because guess what.... Demand went through the roof!
At the end of the day it is 100% up to whoever is selling and whoever is buying (scripters or not). Additionally commission vendors aren't the only means of selling goods so how can you pick one channel of sales and say that's bad for the market (with the reason being "because of scripters")?