Unfortunately some of the dodgy sellers are also high volume ones (I've had the same experience) so it would probably take many many 100s of people getting the same treatment to make a dent in their sales or for eBay to give them the chop.
It's the same with sellers whose stuff breaks down outside the 45 day period. They promise a replacement and don't deliver. Even if you leave follow up feedback, it gets buried in the hundreds of entries since you made the purchase.
They sure do need to be reported but I suppose nothing will be done about them. Since buyers can't block sellers, I keep a list of all the sellers I've bought from who have be less than satisfactory (with a note on what I'd purchased) under the Saved Searches tab - I call it 'The Shame File' so I can check any name that may be familiar. You can make quite a long list under Notes. 
