The answer is quite simple (or at least it should be for a trader )

There is a market, and a demand for such EA's, and if there's a demand, someone will satisfy that demand.

The perfect example of that is the Steintz thread. The guy publishes FULL details of his method. Anyone who took a couple of hours to watch the indicator could see it was a complete non starter. He provided all anyone would ever need to determine for themselves that the method wouldn't work, and yet people still purchased. There are a group of people who would rather believe the hype from a salesman, than their own objective analysis. If you look at this from a wider perspective, thats good, the salesman gets to make a living, rather than being a burden on society, and the market gets some cannon fodder.

You ask why should the buyer lose money. Well they hold the weakest hand, they contribute nothing to the process. At least the coder has a skill, which they used to create a product however poor in quality. If someone is stupid or naive enough to purchase a poor quality product, thats their problem isn't it.

Similarly weak hands entering the market can really only expect one outcome, stronger players will beat them. I cant see anything at all wrong with that, no ones trying to pretend its any other way. If I'm dumb enough to get into a boxing ring with Mike Tyson, chances are I'll get my ass kicked.

If you don't like being ripped off by coders, learn to code for yourself, or go to a decent company. In my experience its very rarely the coders who are to blame, clients simply cannot express their requirements clearly and completely. As a coder, you just cant afford to waste time on people who cant think clearly, you have to cut your losses quickly and move onto the next job.