One of the big problems is that no one actually does read these scripts. You could say "Oh but it's their own fault, duh" but theres a very legitimate argument to be made users going the path of least resistance and that you shouldn't offload this responsibility on your users.

Regarding appImage or rpm, attackers need to build and package these to inject these, while this curl | bash pipe opens up the possiblity of payloads simply by taking over the domain. And this isn't really that far fetched, just think about the Notepad++ update payload recently. The regular package was unaffected while the domain used for the update was taken over.

Then theres also the argument about normalization. Just like he said, this isn't just something he said, this is a very real argument. You don't want to teach users bad habits. Even if / you / inspect the code you get, not everyone will. And ultimately, we should strive to make the Internet a safer place, if only to get less botnets.