1. Kindle Unlimited availability
2. Kindle Countdown Deals
3. Free Promotion Days
4. 70% royalties in certain countries that otherwise only pay 35%
5. Kindle Owner's Lending Library availability
Which of those were there prior to KU?
I always thought all of those were part of the reasons to be in KU.
I cant see any use for them outside of KU.
All of them were prior to KU. Countdown deals are the most recent addition (about a year before KU, if I remember correctly).
The reason you're reacting the way you are is that some of these benefits have eroded in usefulness over time. I think I've said this before, though maybe not in this thread, but free days used to be a big deal. There were literally people who claimed to have built a career with them. (That was when getting free books was a much more novel experience than it is now. It was also before affiliate rules change to penalize affiliates if too much of their volume came from using affiliate links on free offers.)
Similarly, the first countdown deal I did was moderately successful. But as the number of countdown deals increased, the effectiveness declined.
The 70% royalty in countries where you would normally get 35% was probably never much of anything. For me, that meant a higher royalty rate for countries I never got sales in, anyway. Aside from Indian authors, I've only run into a couple of people who've gotten any significant number of sales in India, for example.
There was an additional benefit that no longer exists. When AMS ads for KDP was first introduced, it was exclusively for people in Select. Later, anyone who published through KDP was eligible. The original program was introduced at about the same time as KU. (More ad revenue for Amazon, but less reason to be in Select.)
Some people still do get some mileage out of a judicious use of free days or countdown deals, but nothing like compared to what was happening in the beginning. For most of us, KU is the only substantive benefit of being in Select.