As someone who is newer to posting on Hive I will give this opinion to add to yours.
Curation is NOT well defined or explained to new people. It took me about 3 weeks of posting here to realize that Curation meant I could tip a article and then earn part of that posts earnings. And that some accounts are specifically setup to "curate". I was amazed that at least on PeakD I could not find in the settings or FAQ a good detailed explanation of it.
I was only voting on topics or content that I liked and wanted to reward the author for the effort. And to be quite honest initially I was only tipping accounts of people that I knew from other chains or projects because I was trying to just find more accounts that posted quality content. Obviously since I have expanded to follow and watch community posts and such and then also people I follow who reblog and all that other stuff kind of just compounds over time to get more exposure.
However, if person 1 decides to upvote only articles of people they like or know. Who cares? I can see where some people may get upset. Let's take Holozing for example.
If I delegate say 100 HP to Holozing right, I am earning ZING passively each day for that. THAT is why I would delegate to the Holozing project. I am not delegating to it expecting a automatic upvote on every post I post or even on every Holozing post I make. I think that is unrealistic and unfair expectations.
Like you said some projects/accounts will pay out HIVE rewards for delegating and if that is clearly stated then that may be why you delegate to that account. So unless a account specifically calls out that they are going to upvote all your posts if you Delegate to them, how can you be upset if they don't?
I don't know I guess people a lot of times just expect things when they shouldn't or have unrealistic expectations on things and then choose to be hurt over that and think that life isn't fair or something like that.
But, like I have to tell my kids nearly every day. Life isn't fair. Nobody in the history of the world has claimed that life IS fair so get off that high horse and live in the real world with the rest of us.
If someone is delegating to a account and that account doesn't auto upvote every single one of their posts... then undelegate your HP if that upsets you.
Hive is a free blockchain to do with what you want with what you own. So yeah if a project has thousands of HP delegated to it and it is only upvoting 2 accounts with 100% weight, it would look weird and it could rub a lot of people the wrong way. Well then those people should undelegate and move on. Projects live and die by their community and their users.
TL;DR is everyone is free to do what they want with the HP they have or the HP they were delegated. If someone doesn't like that then stop delegating to them. Easy Enough. Projects require a user base and so projects need to do right by those people but that doesn't mean give everyone a handout either!