OK, I'm back at my PC, so I can type a bit more (and I was supposed not to get involved!). Just to give you some examples of how I handle it, these are all actual encounters that's happened.
Scenario 1.
Community Goal back in a day. I run a fully engineered Conda with biggest shields (not Prismatic, I don't do Powerplay on this character), some HRP's and MRP's, with greatly reduced cargo space due to that.
A wing of 3 interdicts me on my way to the destination station, cargo filled up with goods. No chance of winning in this ship, so I submit. No comms, no other interaction whatsoever, just start shotting at me. I manage to escape to SC. This repeats 4 times (chain interdiction), every time I manage to get a bit closer to my destination. 5th time, in addition to lasers, I get insults thrown at me. Yet again I manage to escape to SC and get to 2 LS to my destination, they pull me back yet again to 50 LS, insults again.
At that point I get bored, clear as day I'm a better pilot, but due to stupid interdiction mechanics they just waste my time. I log to Solo, because in my eyes I've alredy won this 5 times, I can win it another 50. They are just bad pilots.
Next run the very same thing happens. At that point I blocked them, because it was a very clear waste of time time.
Scenario 2.
I live stream. Looking for a double hotspot just outside of populated space, on the southern fringes of the Bubble. Not a soul around.
All of a sudden a wing of 4 drops in. Leading them and throwing insults at me straight away is a guy who got kicked out of our faction for being an extreme Richard to other members. He clearly holds a grudge. None of the people he's with are on my friends list. They destroy my exploration-fitted AspE obviously in no time.
They then start camping at my Fleet Carrier, clearly stream sniping. I ban them on my live stream, but they can obviously watch without being logged in. I don't give up and try to escape another interdiction jumping out to a different system. They follow me there straight away. Clearly stream sniping again.
I don't see any point whatsoever in being their content, nor I need them in my game experience. I block them and enjoy the rest of my stream.
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I have a few more examples like that, but these are the situations where I would block someone. To me this is fair and that's how I always advice people to approach the block function. It's a true blessing against the people you really don't need in your game.
Thankfully this is a perfect way to enjoy Open play, while filtering out pointless and malicious experiences in my game. Because it is my game as much as it is anyone else's and I have the full right to enjoy it on my terms, just as anyone else. And before you jump in with "griefers are people too" and "what about them? can't they enjoy the game as they please?" - of course they can, but definitely NOT at MY expense, end of.
Don't like it? Tough ¯\(ツ)/¯
Plenty of other games that allow for seal bashing with no block function, the exit is this way ---->