Have you actually used other languages like clojure, haskell, kotlin, go or ruby? Python is the weird one here for not allowing multi-line lambdas. There are legitimate and actual useful cases for multi-line lambdas, disallowing them does more harm than good.
If the idea of multi-line alone compromises readability, then why even have multi-line blocks at all? Function, loop and conditional blocks should all at most have one line each. I hope you can see the absurdity of this.
Weird as in it goes against well-established practices. If there are good, compelling reasons to disallow multi-line lambdas, other languages would have adopted it. But no, the opposite is happening, newer and recent languages actually have multi-line lambdas. Get this, even java adopted multi-line lambdas. Crazy right? What's wrong with everyone?
There's nothing wrong with having to name a function. But there is something wrong with not having a choice and being forced to name a multi-line function. Just as you don't want to name every sub-expressions, you don't want to name every blocks of code. Unnecessarily naming things pollutes the namespace.
Where's the strawman? The premise was that functions that spans more than a line should be given a name because they are "unreadable". I have showed that, by this logic, anything that spans more than a line is "unreadable". You can't make special exceptions and say this only applies to lambdas. Lambdas (aka higher-order functions) are blocks of code just as much as anything else.
If the idea of multi-line alone compromises readability, then why even have multi-line blocks at all? Function, loop and conditional blocks should all at most have one line each. I hope you can see the absurdity of this.