I can vaguely remember the Avios being advised, but as I said, the booking engine exUK or other main markets is often more advanced than what people in lesser markets get (with more bells and whistles tagged on).

Hence, I probably didn't see the UK (and US?) one often enough to notice this.

[Also, if you booking complext itins if often throws you back to a more basic booking interface, the swanky ones are usually only polished for simple stuff]