I hate the keyword stuffing but also discovered that when you are shopping and only have a faint understanding of what keywords to search for, the stuffing often helps...

> sellers try to jam as many keywords as possible into the title

I've seen sellers try to match on more searches by mentioning what their product isn't, along the lines of Brand new replacement widgets (NOT original ACME widgets).

> Obviously working around massive limitations in discoverability.

That's the result of competition, rather than search-engine limitations, no?