Interesting conversation. A few thoughts:
First, the sale price of beer.com was what it was because of the elaborate scheme that was executed near perfectly by the guys who sold it. There were a lot more to it than just the domain itself.
That said, I don't think that ultra premium generic domains like beer.com, candy.com, diapers.com and so on have gone down in value. They still would be superb assets for companies selling those things. The money that gets spend on developing new sales channels is huge. For many, an ultra premium generic domain name would definitely lower those costs in a long run.
But.
It's hard to get those kind of domain names anymore. Many are already owned by mega corporations who understand their value. Think Amazon that owns a huge portfolio of generic domains (new g's too) that cover many product categories they're selling. Try buying, say, industrial.supply from them.
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Not everything is going to be a platform like Amazon (referring to
@DomainRecap's quote in OP). Because a) Amazon (or FB, or Google or whatever) will eat you alive, b) it takes years to build those kind of systems, c) it's not exactly easy.
People, businesses will still be selling the stuff they're producing, manufacturing or importing. And they still go after the best domains for their industry when someone in the management figures out the importance of good domains. Any restaurant supply company would want to operate from restaurantsupply.com. And there are many of those companies.
Yes, catchy brandables are great for savvy tech startups who want to look like the next hot sh#%. How many of those companies gets to be that is a different question.
Meanwhile, hundreds and hundreds of 'normal' businesses are founded every day and they're more than happy with natural language names and domains like bestrepair.com, aluminumproducts.com, topseeds.com etc.
Btw, naming and domaining are not the same thing, and different rules apply. Do you want to buy domains that MIGHT become a name of some company or buy domains that are better versions of existing company (domain) names and thus an upgrade for them?