I disagree with calling the question ridiculous. If we’re involving legality like the poster up thread implied with making this illegal then there needs to be some sort of test or rule put in place on what constitutes illegal activity. We currently don’t have one and whenever a new rule is put in place you quickly find out that there is a significant chunk of people who would find anything you think is obviously wrong to be obviously right and vice versa
Arguably third-party apps that are scrapers are somewhere in between these two in acceptability, but that's a question of "are scrapers morally fine and should they be legally allowed", not a question of whether third party clients are to be allowed at all.
The distinction is about whether you should be able to offer something publicly, taking advantage of public infrastructure to do so, and then make demands about what the public do with that.
Companies want to do the electronic equivalent of putting copyrighted media on a billboard in a public square then claiming you need to sign a contract to look at it and then only through special glasses they provide.