Nobody is making enough profit via the Twitter API to make it worth staying on. Twitter is a distant #3 social network that itself has never really made money.

This is being too generous. Facebook, Instagram, and TikTok are all far larger than Twitter. Reddit is also just barely larger than Twitter, though at that scale you have to consider who has more bots. Twitter claims slightly more MAUs than Snapchat, but since Snapchat isn't a viral network it probably has no bots to speak of, making it larger than Twitter in terms of real users.

It's a hard comparison because the value of the Apple ecosystem is so obvious and mutual. Twitter is junk on both sides; unless as a third party dev you just happened to find value in it, in which case you should pay for it.

I understand this is hurting peoples feelings, but it makes complete sense to me from all angles.

I used to use Tweetbot which has now stopped working, as a result I don't use Twitter any more, the advertisers have lost one extra person to sell to.

Which is aligned with Musk's strategy thus far, but there's also a good argument to be made that that product should have never been needed if twitter was providing a decent first party client. They should have wanted to provide that to control the advertising. Letting the third parties take that up was a poor strategy -- business-wise that is, I get that people may have liked it and have used it for a long time and are probably sad to lose it.

They bring the content users want to consume.

Then you're not in the community in which the third party elements(e.g. tweet aggregation, SSO login, fine grained access control) are vital part of. Which may be substantial, or not, and we as the sheep don't know.

When did you start using Twitter? Twitter as we know it today is largely a product of the community and third party developers. Retweets, hashtags, quote tweets, the use of a blue bird symbol; all came from either the community at large or specific third party devs. The fun bots also drive a lot of twitter engagement; honestly they're the only real thing I miss on Mastodon (while some of the most important ones did come across, a lot didn't). Third party software also makes Twitter a support system, a status reporting system... The list goes on.

However, beyond all that, even if there was a good argument for killing the API free tier (there is not), no-one sensible would do it with _one week's notice_. This will alienate even commercial users who would be willing to pay. If you're using your CRM's twitter integration to track customer complaints, say, unless you're huge the free API is probably sufficient today. With one week's notice, even assuming you hear about it the first day (most will not) good look getting a purchase order for the API within a week if your company is even remotely bureaucratic (most are).

The patron saint of Dunning-Kruger presumably thinks it's a good idea, but can't imagine anyone else does.

You don't absolutely need to have your code signed, I can give apps to my friends, they just get a warning about it not being signed and potentially unsafe when it's first installed.