Applets suffered a spin up of the mini VM time. And applets couldn't affect the rendering of the html page, they had their own 'canvas'.
I rather think JS was more appropriate as dev found more use in dynamically altering the very html markup that users saw, and after it was actually rendered.
I think we just need a well designed alternative market place that addresses the OP points. Good search engine, a somewhat reliable review system, ease of use for both sellers and buyers.
One thing to keep in mind, Amazon eCommerce kept loosing money for over a decade. Jeff and the investors focused on the long term. I think this time has come already and they geared up to cash in. They want to cash for today and for yesterday.
To note that this article is some subtle informercial to subscribe to some tool to optimise and automate a sellers ads bidding.
Edit: What a paradox, criticising Amazon for its vampire attitude (takes a cut on the sold price, on shipping costs, on inventory, on returns, on ads).
The points are valid, but the author is trying to sell a tool starting at $29 per month + 4.5% of ads cost. This tool could easily be integrated in the Amazon ads system, it wouldn't surprise me.
I stopped selling on Amazon nearly 10 years ago. FBA was a newly introduced feature which was the trigger for me see Amazon's disrespect for 3rd party sellers.
They skim the seller for the sale (because they do the marketing for you).
They skim on payment processing (it costs them less than they charge)
They skim for exposure (ads are almost a must have to ever appear in search results).
They then skim on delivery via FBA (they charge more than it costs them).
And they skim on warehousing via FBA (the pricing was already unbelievable back then).
Fast forward 10 years, they have started to skim sellers off their business analysis and risk taking effort (They have the data, and will compete with 3rd party sellers on products that sell decently enough, and even place their product before yours).
I've recently taken the time to edited and publish a book that is in the public domain, on their KDP platform, a few days later I see that Amazon is selling that same book and even redirect customer clicks from my page description and book cover to their line item to buy.
I rather think JS was more appropriate as dev found more use in dynamically altering the very html markup that users saw, and after it was actually rendered.