The WhatsApp UI sucks, but they took the hit on UI to focus on reliable sending and fast growth. Those are arguably the features that win over users, not UI.

The way I think about things, consider FB a giant fly-wheel.... You want the external edge to move very quickly and iteratively -- and small dings when you get things wrong don't cost much, but the deeper you go in the stack / towards the infrastructure core (and really the human capital core even below that), you want things to move more slowly and predictably.

The major benefit of foreign keys is that they guarantee referential integrity. For example, say you have customers in one table that may refer to a number of invoices in another. Without foreign keys, you could delete a customer, but forget to remove its invoices, thereby leaving a bunch of orphaned invoices that reference an customer that’s gone.

If an operator ever queries the database directly they’re even more likely to forget deleted_at because normally the ORM does the work for them.

Most Favored Nation (“MFN”) provision (the “MFN safe”)

“The idea makes sense, but perhaps the timing was bad,” says the art market economist and author Magnus Resch, who in June published the book How To Create And Sell NFTs. “Prohibitively high prices and a complicated entry into collecting are the biggest problems with NFTs. But by holding events and educating people you’re building trust.”